<PAGE>   1
    As filed with the Securities and Exchange Commission on December 15, 1998
                                                    Registration No. 333-_______
--------------------------------------------------------------------------------
                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549

                                 ---------------

                                    FORM S-4
                             REGISTRATION STATEMENT
                                      UNDER
                           THE SECURITIES ACT OF 1933

                                 ---------------

                         UNITED SECURITY BANCORPORATION
             (Exact name of registrant as specified in its charter)

   WASHINGTON                     6022                           91-1259511
(State or other             (Primary standard                 (I.R.S. employer 
jurisdiction of                industrial                    identification no.)
incorporation or             classification  
 organization)                code number)

   9506 NORTH NEWPORT HIGHWAY, SPOKANE, WASHINGTON 99218-1200 (509) 467-6949
         (Address, including zip code, and telephone number, including
             area code, of registrant's principal executive offices)

                                   ----------

                                RICHARD C. EMERY
                      President and Chief Executive Officer
                           9506 North Newport Highway
                         Spokane, Washington 99218-1200
                                 (509) 467-6949

           (Name, address, including zip code, and telephone number,
                   including area code, of agent for service)

                                   -----------

                          Copies of communications to:

   STEPHEN M. KLEIN, ESQ.                             GLEN P. GARRISON, ESQ.
 WILLIAM E. BARTHOLDT, ESQ.                           LUCAS D. SCHENCK, ESQ.
      Graham & Dunn PC                                Keller Rohrback, L.L.P.
1420 Fifth Avenue, 33rd Floor                               Suite 3200
  Seattle, Washington 98101                             1201 Third Avenue,
                                                  Seattle, Washington 98101-3052

 APPROXIMATE DATE OF COMMENCEMENT OF PROPOSED SALE OF SECURITIES TO THE PUBLIC:
                      The date of mailing of the enclosed 
               Prospectus/Joint Proxy Statement to stockholders of
                         United Security Bancorporation
                       and Bancwest Financial Corporation.

      If the securities being registered on this Form are being offered in
         connection with the formation of a holding company and there is
       compliance with General Instruction G, check the following box. [ ]

                         CALCULATION OF REGISTRATION FEE

<TABLE>
<CAPTION>
=========================================================================================================
Title of Each                                Proposed Maximum    Proposed Maximum          Amount of
Class of Securities        Amount Being      Offering Price      Aggregate                 Registration
Being Registered           Registered(1)     Per Share(2)(3)     Offering Price(3)         Fee
=========================================================================================================
<S>                        <C>               <C>                 <C>                       <C>      
Common Stock,
   No Par Value            1,900,000         $6.73               $12,785,346.58            $3,554.33
=========================================================================================================
</TABLE>

(1) Represents the estimated maximum number of shares of United Security
    Bancorporation's common stock, no par value ("USBN common stock"), issuable
    in exchange for the 365,541 shares of Bancwest Financial Corporation's
    common stock, no par value ("BFC common stock"), that are outstanding and
    the 24,613 shares of BFC common stock subject to outstanding options, under
    the terms of the Agreement and Plan of Merger described in this Registration
    Statement.

(2) Represents the maximum price per share of USBN common stock issuable in
    exchange for BFC common stock, based on the Merger exchange ratio.

(3) Estimated solely for the purpose of calculating the registration fee
    pursuant to Rule 457(f)(2) under the Securities Act of 1933, as amended
    ("1933 Act"), on the basis of the per share book value of the BFC common
    stock at December 1, 1998.

                                    ---------

         THE REGISTRANT HEREBY AMENDS THIS REGISTRATION STATEMENT ON SUCH DATE
OR DATES AS MAY BE NECESSARY TO DELAY ITS EFFECTIVE DATE UNTIL THE REGISTRANT
FILES A FURTHER AMENDMENT THAT SPECIFICALLY STATES THAT THIS REGISTRATION
STATEMENT SHALL THEREAFTER BECOME EFFECTIVE IN ACCORDANCE WITH SECTION 8(a) OF
THE 1933 ACT, OR UNTIL THIS REGISTRATION STATEMENT BECOMES EFFECTIVE ON SUCH
DATE AS THE SECURITIES AND EXCHANGE COMMISSION, ACTING PURSUANT TO SAID SECTION
8(a), MAY DETERMINE.

<PAGE>   2


                          [USBN LETTER TO STOCKHOLDERS]



TO OUR STOCKHOLDERS:

         You are cordially invited to attend a special meeting of the
stockholders of United Security Bancorporation ("USBN") to be held on January
___, 1999, at [a.m./p.m.] local time at ______________, Spokane, Washington.

         The boards of USBN and of Bancwest Financial Corporation ("BFC") have
agreed that USBN will acquire The Bank of the West (the "Bank"), which is a
subsidiary of BFC, in a Merger transaction. The Bank will become a subsidiary of
USBN, but will continue to operate under its current name and management and in
its current locations. Following the Merger, BFC stockholders will become
stockholders of USBN.

         The Merger Agreement is described in the accompanying Prospectus/Joint
Proxy Statement and a copy is attached to that document. If the Merger is
completed, each BFC stockholder will receive 4.7038 shares of USBN common stock
for each share of BFC common stock, plus an additional amount, as applicable,
based on BFC's net earnings between January 1, 1999 and the date of the Merger.
Your board of directors has received an opinion from Pacific Crest Securities,
Inc. to the effect that, subject to the factors and assumptions described in the
opinion, the consideration to be paid to BFC stockholders in the Merger is fair,
from a financial point of view, to USBN's stockholders.

         YOUR VOTE IS VERY IMPORTANT. THE MERGER CANNOT BE COMPLETED UNLESS THE
STOCKHOLDERS OF BOTH USBN AND BFC APPROVE IT.

         Whether or not you plan to attend the special stockholders' meeting,
please take the time to vote by completing and mailing the enclosed proxy to us.
If you decide to attend the special stockholders' meeting, you may vote in
person even though you have already submitted a proxy.

         We urge you to review the enclosed Prospectus/Joint Proxy Statement and
to consider your vote carefully. If you have any questions regarding this
material in advance of the special stockholders' meeting, please call Richard
Emery at (509) 467-6949.

         On behalf of your Board of Directors, we recommend that you vote FOR
approval of the Merger Agreement.

         Yours truly,                      Yours truly,



         William C. "Bud" Dashiell         Richard C. Emery
         Chairman                          President and Chief Executive Officer



         PLEASE COMPLETE, SIGN, DATE AND RETURN THE ENCLOSED PROXY FORM



<PAGE>   3



                         UNITED SECURITY BANCORPORATION

                    NOTICE OF SPECIAL MEETING OF STOCKHOLDERS
                          TO BE HELD JANUARY ____, 1999


TO THE STOCKHOLDERS OF UNITED SECURITY BANCORPORATION:

         NOTICE IS HEREBY GIVEN that pursuant to call of its Board of Directors,
a Special Meeting of Stockholders of United Security Bancorporation ("USBN"), a
Washington corporation, will be held on January ___, 1999, at ______ [a.m./p.m.]
local time, at ________________, Spokane, Washington. The Special Meeting is for
the following purposes:

         1. MERGER AGREEMENT. To consider and vote upon a proposal to approve
the Agreement and Plan of Merger ("Merger Agreement"), dated as of November 10,
1998 among USBN, Bancwest Financial Corporation ("BFC") and Bank of the West, a
Washington state bank and subsidiary of BFC ("the Bank"), under the terms of
which BFC will be merged with and into USBN, and the Bank will become a
subsidiary of USBN, as more fully described in the accompanying Prospectus/Joint
Proxy Statement. The Merger Agreement is attached as APPENDIX A to the
Prospectus/Joint Proxy Statement.

         2. OTHER MATTERS. To act upon such other matters as may properly come
before the Special Meeting or any adjournment thereof.

         Only holders of record of USBN common stock, no par value per share, at
5:00 p.m. on December 21, 1998 (the record date for the Special Meeting), are
entitled to notice of, and to vote at, the Special Meeting or any adjournments
or postponements of the meeting. The affirmative vote of the holders of
two-thirds or more of the outstanding shares of USBN common stock is required
for approval of the Merger Agreement. As of _________________, 1998, there were
__________ shares of USBN common stock outstanding.

         All USBN stockholders are cordially invited to attend the Special
Meeting personally. Whether or not you are able to do so, it is important that
you complete, sign, date, and promptly return the accompanying proxy in the
enclosed postage-paid envelope in order to vote your shares of USBN common
stock. Stockholders may revoke proxies previously submitted by completing a
later-dated proxy, by written revocation delivered to USBN's Secretary at or
prior to the Special Meeting, or by appearing and voting at the Special Meeting
in person. Attendance at the Special Meeting will not of itself revoke a
previously submitted proxy.

                                       By Order of the Board of Directors,



                                       Jackie Barnard
                                       Secretary
Spokane, Washington
December ___, 1998



YOUR VOTE IS IMPORTANT REGARDLESS OF THE NUMBER OF SHARES YOU OWN, AND WHETHER
OR NOT YOU PLAN TO ATTEND THE SPECIAL MEETING. APPROVAL OF THE MERGER REQUIRES
THE AFFIRMATIVE VOTE OF HOLDERS OF TWO-THIRDS OF THE OUTSTANDING SHARES OF USBN
COMMON STOCK. IN ORDER TO ENSURE THAT THE REQUISITE VOTES ARE OBTAINED AND A
QUORUM IS ATTAINED, WE URGE YOU TO SIGN, DATE AND RETURN THE ENCLOSED PROXY
FORM.



<PAGE>   4


                             BFC STOCKHOLDER LETTER



TO OUR STOCKHOLDERS:

         You are cordially invited to attend a special meeting of stockholders
("Special Meeting") of Bancwest Financial Corporation ("BFC"), to be held at
_____________________________________, Walla Walla, Washington, on January ___,
1999, at _______ o'clock ___.m., local time.

         The Notice of Special Meeting of Stockholders and Prospectus/Joint
Proxy Statement that appear on the following pages describe the formal business
to be transacted at the meeting. At the meeting, you will be asked to consider
and vote upon a proposal to approve the Agreement and Plan of Merger dated as of
November 10, 1998 (the "Merger Agreement") by and among United Security
Bancorporation ("USBN"), BFC and Bank of the West (the "Bank"). The Merger
Agreement provides that BFC will be merged with USBN and thereafter the Bank
will operate as a wholly owned subsidiary of USBN.

         Upon consummation of the Merger, each share of BFC common stock will be
converted into the right to receive 4.7038 shares of USBN common stock, adjusted
upwards, if applicable, to account for the Bank's net income between January 1,
1999, and the date the Merger occurs. The last reported sale price of USBN
common stock on the Nasdaq National Market (symbol: "USBN") on ________________,
1998 was $_______ per share. You are urged to review carefully the enclosed
Prospectus/Joint Proxy Statement, which contains a more complete description of
the terms of the Merger.

         At the Special Meeting, you will also be asked to confirm the present
composition of the BFC board of directors and adopt the acts of such board as
the acts of the BFC board ("Director Confirmation").

         The board of directors of BFC determined that the Merger Agreement is
in the best interest of the stockholders of BFC and unanimously approved the
Merger Agreement. THE BOARD RECOMMENDS THAT YOU VOTE FOR APPROVAL OF THE MERGER
AGREEMENT AND THE DIRECTOR OF CONFIRMATION. Approval of the Merger Agreement
requires the affirmative vote of two-thirds of the outstanding shares of BFC
common stock. Approval of the Director Confirmation requires the affirmative
vote of a majority of the votes cast at the Special Meeting.

         It is very important that your shares be represented at the meeting,
regardless of whether you plan to attend in person. A failure to vote, either by
not returning the enclosed proxy or by checking the "Abstain" box, will have the
same effect as a vote against approval of the Merger Agreement or the Director
Confirmation. To assure that your shares are represented in voting on these very
important matters, PLEASE SIGN, DATE AND RETURN THE ENCLOSED PROXY CARD in the
enclosed postage-prepaid envelope whether or not you plan to attend the meeting.
If you are a stockholder of record and do attend, you may, if you wish, revoke
your proxy and vote your shares in person at the meeting.

         On behalf of the Board of Directors, I urge you to vote FOR approval of
the Merger Agreement and the Director Confirmation.

                                       Sincerely,



                                       Wes Colley
                                       Chairman of the Board




<PAGE>   5



                         BANCWEST FINANCIAL CORPORATION
                               30 WEST MAIN STREET
                          WALLA WALLA, WASHINGTON 99362

                    NOTICE OF SPECIAL MEETING OF STOCKHOLDERS

TO THE STOCKHOLDERS OF BANCWEST FINANCIAL CORPORATION:

         NOTICE IS HEREBY GIVEN that a Special Meeting of Stockholders of
Bancwest Financial Corporation ("BFC") will be held at _____________________,
Walla Walla, Washington, on __________ January ___, 1999, at ______ __.m., for
the following purposes:

         1. Agreement and Plan of Merger. To consider and vote upon a proposal
to approve the Agreement and Plan of Merger dated as of November 10, 1998
("Merger Agreement") by and among Bancwest Financial Corporation ("BFC"), Bank
of the West (the "Bank") and United Security Bancorporation ("USBN"), a copy of
which is set forth in APPENDIX A to the accompanying Prospectus/Joint Proxy
Statement, pursuant to which BFC would merge into USBN and the Bank will become
a wholly owned subsidiary of USBN, all on and subject to the terms and
conditions contained therein.

         2. Director Confirmation. To consider the vote upon a proposal to
confirm the present composition of the BFC board of directors, and to adopt the
acts of such board as the acts of the BFC board of directors (the "Director
Confirmation").

         3. To consider and act upon such other matters as may properly come
before the meeting or any adjournments thereof.

         Only those stockholders of record at the close of business on
_______________, 1998 shall be entitled to notice of, and to vote at, the
meeting or any adjournments thereof. The affirmative vote of the holders of
two-thirds of the outstanding shares of BFC common stock is required for
approval of the Merger Agreement. The affirmative vote of the holders of a
majority of the votes cast at the BFC Special Meeting is required for approval
of the Director Confirmation.

         BFC stockholders have the right to dissent from the merger and obtain
payment of the fair value of their shares of BFC common stock under the
applicable provisions of Washington law. In order to perfect dissenters' rights,
BFC stockholders must send a notice to BFC before the Special Meeting on January
___, 1999 and must not vote in favor of the merger by proxy or otherwise. A copy
of the applicable Washington statutory provisions regarding dissenters' rights
is set forth in APPENDIX E to the accompanying Prospectus/Joint Proxy Statement
and a summary of such provisions is set forth under "THE MERGER -- Dissenters'
Rights" beginning on page ___. Further information regarding voting rights and
the business to be transacted at the meeting is given in the accompanying
Prospectus/Joint Proxy Statement.

         The Board of Directors of BFC unanimously recommends that stockholders
vote "FOR" approval of the Merger Agreement and the Director Confirmation.

                                       Sincerely,



                                       Mark Graves
                                       Secretary

YOUR VOTE IS IMPORTANT REGARDLESS OF THE NUMBER OF SHARES YOU OWN. WHETHER OR
NOT YOU PLAN TO ATTEND THE MEETING, PLEASE SIGN, DATE AND PROMPTLY RETURN THE
ACCOMPANYING PROXY FORM USING THE ENCLOSED POSTAGE-PREPAID ENVELOPE. IF FOR ANY
REASON YOU SHOULD DESIRE TO REVOKE YOUR PROXY, YOU MAY DO SO AT ANY TIME BEFORE
IT IS VOTED AT THE MEETING.



<PAGE>   6


                              JOINT PROXY STATEMENT
                       UNITED SECURITY BANCORPORATION AND
                         BANCWEST FINANCIAL CORPORATION

                                   PROSPECTUS
                         UNITED SECURITY BANCORPORATION

          The boards of directors of United Security Bancorporation ("USBN") and
Bancwest Financial Corporation ("BFC") have agreed that BFC will merge with and
into USBN. When the merger occurs, the separate existence of BFC will cease and
Bank of the West ("the Bank"), which is now a subsidiary of BFC, will become a
subsidiary of USBN. The Bank will remain a separate entity and will operate in
its current localities.

         In the Merger, BFC stockholders will receive shares of USBN common
stock in exchange for their shares of BFC common stock. If the Merger is
completed, BFC stockholders will receive 4.7038 shares of USBN common stock for
each share of BFC common stock that they own, adjusted upwards, if applicable,
based on the Bank's net income between January 1, 1999 and the date that the
Merger occurs. See "THE MERGER - Basic Terms of the Merger".

         USBN common stock trades on the Nasdaq National Market under the symbol
"USBN". The reported sales price for USBN common stock was $_______ on December
___, 1998, the most recent date for which it was practicable to obtain
information prior to the printing of this Prospectus/Joint Proxy Statement. BFC
common stock does not trade on any market, thus no current market price is
available.

         THE MERGER CANNOT BE COMPLETED UNLESS BOTH THE USBN AND THE BFC
STOCKHOLDERS APPROVE IT. USBN has scheduled a special stockholders meeting, to
vote on the Merger, for January ___, 1999. See "USBN SPECIAL STOCKHOLDER
MEETING". BFC has scheduled a special stockholders meeting, to vote on the
Merger, for January ___, 1999. See "BFC SPECIAL STOCKHOLDER MEETING". At the BFC
Special Stockholder Meeting, BFC stockholders will also vote on the Director
Confirmation. See "DIRECTOR CONFIRMATION."

         This document also serves as the prospectus of USBN, filed as a part of
a Registration Statement on Form S-4 with the Securities and Exchange Commission
(the "SEC"). The Registration Statement registers the shares of USBN common
stock that will be issued to BFC stockholders in the Merger. This
Prospectus/Joint Proxy Statement provides you with detailed information about
the Merger, and we urge you to read it carefully. In addition, you may obtain
additional information about USBN from documents that it has filed with the SEC.
See "WHERE YOU CAN FIND MORE INFORMATION".

                           ---------------------------

         NEITHER THE SEC NOR ANY STATE SECURITIES COMMISSION HAS APPROVED OR
DISAPPROVED OF THESE SECURITIES OR DETERMINED IF THIS PROSPECTUS/JOINT PROXY
STATEMENT IS TRUTHFUL OR COMPLETE. ANY REPRESENTATION TO THE CONTRARY IS A
CRIMINAL OFFENCE.

         THE SHARES OF USBN COMMON STOCK TO BE ISSUED IN THE MERGER ARE NOT
SAVINGS OR DEPOSIT ACCOUNTS OR OTHER OBLIGATIONS OF A BANK AND ARE NOT INSURED
BY A BANK INSURANCE FUND OF THE FEDERAL DEPOSIT INSURANCE CORPORATION OR ANY
OTHER GOVERNMENT AGENCY OR INSTRUMENTALITY.

         THIS PROSPECTUS/JOINT PROXY STATEMENT DOES NOT COVER ANY RESALE OF THE
SECURITIES TO BE RECEIVED BY BFC STOCKHOLDERS IN THE MERGER, AND NO PERSON IS
AUTHORIZED TO MAKE USE OF THIS PROSPECTUS/JOINT PROXY STATEMENT IN CONNECTION
WITH ANY SUCH RESALE.

                           ---------------------------

      This Prospectus/Joint Proxy Statement is dated December ___, 1998, and
        is first being mailed to USBN stockholders on December ___, 1998,
                  and to BFC stockholders on December __, 1998.



<PAGE>   7




                              [INSIDE FRONT COVER]

         THIS PROSPECTUS/JOINT PROXY STATEMENT INCORPORATES IMPORTANT BUSINESS
AND FINANCIAL INFORMATION ABOUT USBN THAT IS NOT INCLUDED OR DELIVERED WITH THIS
DOCUMENT. SUCH INFORMATION IS AVAILABLE WITHOUT CHARGE TO USBN AND BFC
STOCKHOLDERS UPON WRITTEN OR ORAL REQUEST. CONTACT USBN AT 9506 NORTH NEWPORT
HIGHWAY, SPOKANE, WASHINGTON 99218-1200, ATTN: JACKIE BARNARD. USBN'S TELEPHONE
NUMBER IS (509) 467-6949.

         TO OBTAIN TIMELY DELIVERY OF REQUESTED DOCUMENTS PRIOR TO THE SPECIAL
STOCKHOLDERS MEETINGS, YOU MUST REQUEST THEM NO LATER THAN JANUARY _, 1999 IN
THE CASE OF THE USBN MEETING, AND JANUARY _, 1999 IN THE CASE OF THE BFC
MEETING, WHICH IS FIVE BUSINESS DAYS PRIOR TO THE DATES OF SUCH MEETINGS.

         Also see "WHERE YOU CAN FIND MORE INFORMATION" and "INFORMATION
INCORPORATED BY REFERENCE".


<PAGE>   8


                                TABLE OF CONTENTS

<TABLE>
<CAPTION>
                                                                                                    PAGE
                                                                                                   ----
<S>                                                                                                <C>
SUMMARY..............................................................................................1

         THE DEAL AT A GLANCE........................................................................1

         INITIAL QUESTIONS AND ANSWERS ABOUT THE MERGER..............................................1

         ADDITIONAL IMPORTANT INFORMATION ABOUT THE MERGER...........................................3

                  USBN Special Stockholders Meeting..................................................3
                  BFC Special Stockholders Meeting...................................................3
                  Opinion of USBN Financial Advisor..................................................3
                  Opinion of BFC Financial Advisor...................................................4
                  Conditions to the Merger...........................................................4
                  Stock Option Agreement.............................................................4
                  Amendment or Termination of the Merger Agreement...................................5
                  Ownership of USBN After the Merger.................................................5
                  USBN and BFC Directors and Officers After the Merger...............................5
                  Accounting Treatment of the Merger.................................................5
                  Dissenters' Rights of Appraisal....................................................5
                  Interests of Certain Persons in the Merger.........................................6
                  Comparison of Stockholders' Rights.................................................6
                  Trading Markets....................................................................6

         BFC DIRECTOR CONFIRMATION...................................................................6


STOCK PRICE AND DIVIDEND INFORMATION.................................................................7

                  USBN     ..........................................................................7
                  BFC      ..........................................................................7
                  Recent Stock Price Data............................................................8

EQUIVALENT PER COMMON SHARE DATA.....................................................................9


SELECTED HISTORICAL FINANCIAL DATA..................................................................11


USBN SPECIAL STOCKHOLDER MEETING....................................................................14

                  Date, Time and Place..............................................................14
                  Purpose...........................................................................14
                  Record Date; Shares Outstanding and Entitled to Vote..............................14
                  Vote Required.....................................................................14
                  Voting, Solicitation, and Revocation of Proxies...................................14

BFC SPECIAL STOCKHOLDER MEETING.....................................................................15

                  Date, Time and Place..............................................................15
                  Purpose...........................................................................15
                  Record Date; Shares Outstanding and Entitled to Vote..............................15
                  Vote Required.....................................................................15
                  Voting, Solicitation, and Revocation of Proxies...................................16
</TABLE>



                                       i


<PAGE>   9



<TABLE>
<CAPTION>
                                                                                                    PAGE
                                                                                                   ----
<S>                                                                                                <C>
BACKGROUND OF AND REASONS FOR THE MERGER............................................................16

                  Background of the Merger..........................................................16
                  USBN'S Reasons for the Merger.....................................................17
                  Recommendation of USBN Board of Directors.........................................18
                  Opinion of USBN's Financial Advisor...............................................18
                  BFC's Reasons for the Merger......................................................19
                  Recommendation of BFC Board of Directors..........................................20
                  Opinion of BFC's Financial Advisors...............................................20

THE MERGER..........................................................................................23

                  Basic Terms of the Merger.........................................................23
                  Cash for Fractional Shares........................................................24
                  Exchange of BFC Stock Certificates................................................24
                  Conditions to Consummation of the Merger; Regulatory Approvals....................25
                  BFC Stock Option Agreement........................................................26
                  Amendment or Termination of the Merger Agreement: Termination Fees................26
                  Conduct of Business Pending the Merger............................................27
                  Directors and Executive Officers After the Merger.................................28
                  Employee Benefit Plans............................................................28
                  Interests of Certain Persons in the Merger........................................28
                  Federal Income Tax Treatment of the Merger........................................29
                  Accounting Treatment of Merger....................................................30
                  Dissenters' Rights of Appraisal...................................................30
                  Resale of USBN Common Stock.......................................................32
                  No Solicitation...................................................................32
                  Expenses..........................................................................32

DIRECTOR CONFIRMATION...............................................................................33


PRO FORMA CONDENSED COMBINED UNAUDITED FINANCIAL STATEMENTS.........................................34


BUSINESSES OF THE PARTIES TO THE MERGER.............................................................42

                  Information Concerning USBN.......................................................42
                  Information Concerning BFC........................................................43
                  Security Ownership of Certain Beneficial Owners and Management of BFC.............46

BFC MANAGEMENT'S DISCUSSION AND ANALYSIS OF FINANCIAL CONDITION AND RESULTS OF OPERATIONS...........47

                  Financial Conditions and Results of Operations for the Nine Months Ended
                           September 30, 1998 and 1997..............................................47
                  Financial Conditions and Results of Operations for the Years Ended
                           December 31, 1997 and 1996...............................................47
                  Loan Quality, Liquidity and Capital...............................................48
                  Quantitative and Qualitative Disclosure About Market Risk.........................49

SUPERVISION AND REGULATION..........................................................................51


DESCRIPTION OF USBN CAPITAL STOCK...................................................................55


COMPARISON OF CERTAIN RIGHTS OF HOLDERS OF USBN AND BFC COMMON STOCK................................56
</TABLE>



                                       ii


<PAGE>   10


<TABLE>
<CAPTION>
                                                                                                    PAGE
                                                                                                   ----
<S>                                                                                                <C>
CERTAIN LEGAL MATTERS...............................................................................59

EXPERTS.............................................................................................59

WHERE YOU CAN FIND MORE INFORMATION.................................................................60

INFORMATION INCORPORATED BY REFERENCE...............................................................60

OTHER MATTERS.......................................................................................61
</TABLE>

         APPENDIX A - Agreement and Plan of Merger

         APPENDIX B - Opinion of USBN Financial Advisor

         APPENDIX C - Opinion of BFC Financial Advisor

         APPENDIX D - Stock Option Agreement between USBN and BFC

         APPENDIX E - Dissenters' Rights of Appraisal - RCW 23B.13.010



                                      iii



<PAGE>   11


                                     SUMMARY

         This Summary highlights selected information from this document and may
not contain all of the information that is important to you. To understand the
Merger fully and for a more complete description of the legal terms of the
Merger, you should read carefully this entire document and the documents we have
referred you to. See "WHERE YOU CAN FIND MORE INFORMATION."

                              THE DEAL AT A GLANCE

THE PARTIES       -        United Security Bancorporation ("USBN"), a multi-bank
                           holding company based in Spokane, Washington;
                           Bancwest Financial Corporation ("BFC"), a bank
                           holding company based in Walla Walla, Washington; and
                           the Bank of the West (the "Bank"), a Washington state
                           bank and the subsidiary of BFC.

TRANSACTION       -        A merger between USBN and BFC.

EFFECT            -        BFC will cease to exist; its current subsidiary, the
                           Bank, will become a subsidiary of USBN.

                  -        BFC stockholders will become USBN stockholders.

CONSIDERATION     -        BFC stockholders will receive 4.7038 shares of USBN
                           stock for each share of BFC common stock; possibly
                           more, to the extent of BFC's 1999 net income between
                           January 1, 1999 and the closing.

CONDITIONS        -        There are a number of conditions that must be
                           satisfied before the Merger can occur, INCLUDING
                           APPROVAL BY USBN AND BFC STOCKHOLDERS AND REGULATORY
                           AUTHORITIES.

                 INITIAL QUESTIONS AND ANSWERS ABOUT THE MERGER

Q:       Who are the parties to the Merger?

A:       USBN. USBN is a multi-bank holding company headquartered in Spokane,
         Washington. USBN owns four banks:

         -        United Security Bank, a Washington state-chartered bank;

         -        Home Security Bank, a Washington state-chartered bank;

         -        Bank of Pullman, an Idaho state-chartered bank; and

         -        Grant National Bank, a national bank

         USBN also owns USB Insurance (Washington) (an insurance agency), USB
         Leasing (Washington) (a leasing company), and USB Mortgage (Washington)
         (a mortgage company). USBN's principal executive offices are located at
         9506 North Newport Highway, Spokane, Washington 99218-1200 and its
         telephone number is (509) 467-6949.

         USBN conducts its banking business through 27 branches located in
         communities throughout Eastern Washington, including Spokane and a
         branch in Moscow, Idaho. At September 30, 1998, USBN had total
         consolidated assets of approximately $404.7 million, net loans of
         approximately $282.2 million and deposits of approximately $354.8
         million. See "BUSINESSES OF THE PARTIES TO THE MERGER - Information
         Concerning USBN."



                                       1

<PAGE>   12


         Additional information concerning USBN is included in the USBN
         documents incorporated by reference in this Prospectus/Joint Proxy
         Statement. See "INFORMATION INCORPORATED BY REFERENCE."

         BFC. BFC is a bank holding company headquartered in Walla Walla,
         Washington. The Bank is the sole subsidiary of BFC. The Bank has its
         headquarters and two branch locations in Walla Walla, and has full
         service branches in the communities of Waitsburg and Dayton, east of
         Walla Walla in Southeastern Washington. At September 30, 1998, BFC had
         consolidated assets of approximately $104.1 million, net loans of
         approximately $70.3 million and deposits of approximately $90.2
         million. See "BUSINESSES OF THE PARTIES TO THE MERGER - Information
         Concerning BFC."

Q.       What is the effect of the Merger?

A.       If the Merger occurs, BFC will merge with and into USBN, and its
         separate existence will cease. The Bank, which is currently a
         subsidiary of BFC, will become a subsidiary of USBN. The Bank will
         continue its current operations, under its current name. Unless they
         dissent from the Merger, BFC stockholders will receive shares of USBN
         common stock in exchange for the shares of BFC that they now own, and
         will become USBN stockholders. See "THE MERGER - Basic Terms of the
         Merger."

Q:       Why are the companies proposing to enter into the Merger?

A:       Because USBN and BFC believe that the Merger will provide both
         companies with substantial benefits, and will allow the Bank to better
         serve its customers. Because of USBN's financial and technology
         resources, the Bank will be able to offer additional products and
         services, while maintaining continuity of services to its current
         customers. USBN common stock is more actively traded than BFC common
         stock, and BFC stockholders can be expected to benefit from the
         increased liquidity in owning USBN common stock. For a more complete
         discussion of the reasons that the board of directors of USBN and BFC
         approved the Merger, see "BACKGROUND OF AND REASONS FOR THE MERGER".

         THE BOARD OF DIRECTORS OF USBN RECOMMENDS THAT USBN STOCKHOLDERS VOTE
         IN FAVOR OF THE PROPOSED MERGER, AND THE BOARD OF DIRECTORS OF BFC
         RECOMMENDS THAT BFC STOCKHOLDERS VOTE IN FAVOR OF THE PROPOSED MERGER.

Q:       What will BFC stockholders receive in the Merger?

A:       BFC stockholders will receive 4.7038 shares of USBN common stock for
         each share of BFC common stock. The number of USBN shares per BFC share
         will be adjusted upwards, based upon BFC's net income between January
         1, 1999 and the Merger effective date. The manner in which this
         adjustment would operate, and an example of such an adjustment, are set
         forth at "THE MERGER - Basic Terms of the Merger."

Q:       What do I need to do now?

A:       Just read this Prospectus/Joint Proxy Statement and mail your signed
         proxy card in the enclosed return envelope as soon as possible, so that
         your shares can be represented at the USBN or BFC special stockholders
         meeting. The USBN special meeting will take place on January ____, 1999
         at ______ [a.m./p.m.]. The BFC special meeting will take place on
         January ____, 1999 at _______ [a.m./p.m.] See "USBN SPECIAL MEETING" or
         "BFC SPECIAL MEETING," as appropriate.



                                       2

<PAGE>   13


Q:       Can I change my vote after I have mailed my signed proxy card?

A:       Yes. You can change your vote at any time before your proxy is voted at
         the special meeting. You can do this in one of three ways. First, you
         can send a written notice stating that you would like to revoke your
         proxy. Second, you can complete and submit a new proxy card. If you
         choose either of these two methods, you must submit your notice of
         revocation or your new proxy card to USBN or BFC, as the case may be.
         Third, you can attend the special meeting and vote in person. Simply
         attending the meeting, however, will not revoke your proxy. See "USBN
         SPECIAL MEETING - Voting, Solicitation and Revocation of Proxies" or
         "BFC SPECIAL MEETING - Voting Solicitation and Revocation Proxies."

Q:       Should BFC stockholders send their stock certificates in now?

A:       No. After the Merger is completed, USBN will send BFC stockholders
         written instructions for exchanging their stock certificates. See "THE
         MERGER - Exchange of Stock Certificates."

Q:       When do you expect the Merger to be completed?

A:       USBN and BFC are working towards completing the Merger as quickly as
         possible. In addition to USBN and BFC stockholder approval, certain
         regulatory approvals must be obtained, and there are other conditions
         to completing the Merger. USBN and BFC expect the Merger to be
         completed as early as January 31, 1999.
         See "THE MERGER - Basic Terms of the Merger."

Q:       What are the tax consequences of the Merger?

A:       The Merger generally will be tax-free to you for federal income tax
         purposes. To review the tax consequences to stockholders in greater
         detail, see "THE MERGER - Certain Federal Income Tax Consequences of
         the Merger."

                ADDITIONAL IMPORTANT INFORMATION ABOUT THE MERGER

USBN SPECIAL STOCKHOLDERS MEETING

         A special meeting of USBN's stockholders will be held on January _____,
1999 at __ p.m. at ________________, Spokane, Washington. At the meeting, USBN
stockholders will be asked to approve the Merger and the Merger Agreement. The
Merger must be approved by the owners of two-thirds (2/3) of all of the USBN
common stock outstanding on December 21, 1998, which is the record date for the
USBN special meeting. See "USBN SPECIAL STOCKHOLDERS MEETING".

BFC SPECIAL STOCKHOLDERS MEETING

         A special meeting of BFC's stockholders will be held on January _____,
1999 at __ p.m. at _________, Walla Walla, Washington. At the meeting, BFC
stockholders will be asked to approve the Merger and the Merger Agreement. The
Merger must be approved by the owners of two-thirds (2/3) of all of the BFC
common stock outstanding on ______, 199__, which is the record date for the BFC
special meeting. See "BFC SPECIAL STOCKHOLDERS MEETING".

OPINION OF USBN FINANCIAL ADVISOR

         USBN asked its financial advisor, Pacific Crest Securities ("PCS"), for
advice on the fairness of the amount that it is offering to BFC stockholders in
the Merger. PCS performed a number of analyses in which it 



                                       3

<PAGE>   14


compared the companies' historical financial performances, compared the
financial terms of the Merger with other similar transactions, and analyzed
other matters. PCS delivered an opinion to USBN that the Merger is fair, from a
financial point of view, to USBN's stockholders. PCS's opinion is described at
"BACKGROUND OF AND REASONS FOR THE MERGER - Opinion of USBN Financial Advisor",
and a copy of the opinion is attached at APPENDIX B.

OPINION OF BFC FINANCIAL ADVISOR

         BFC asked its financial advisor, Columbia Financial Advisors, Inc.
("CFA") for advice on the fairness of the amount that is being received by BFC
stockholders in the Merger. CFA performed a number of analyses in which it
compared the companies' historical financial performances, compared the
financial terms of the Merger with other similar transactions, and analyzed
other matters. CFA delivered an opinion to BFC that the Merger is fair, from a
financial point of view, to BFC's stockholders. CFA's opinion is described at
"BACKGROUND AND REASONS FOR THE MERGER - Opinion of BFC Financial Advisor", and
a copy of CFA's opinion is attached as APPENDIX C.

CONDITIONS TO THE MERGER

         To complete the Merger, USBN and BFC must satisfy a number of
conditions in addition to approval by the USBN and BFC stockholders. Such
conditions include:

         o        no law or injunction may effectively prohibit the Merger;

         o        USBN and BFC must receive all necessary approvals of
                  governmental authorities; and

         o        USBN and BFC must receive a legal opinion that the Merger will
                  be treated as a tax-free reorganization under the Internal
                  Revenue Code.

         Additionally, USBN may terminate the Merger Agreement if (a) the total
amount of cash it would be required to pay for fractional shares and to BFC
stockholders who dissent from the Merger exceeds 10% of the total Merger
purchase price, or (b) if USBN determines that the Merger will not be treated
for accounting purposes as a "pooling of interests".

         Certain conditions to the Merger may be waived by the company entitled
to assert the condition. For a more complete discussion of the conditions to the
completion of the Merger, see " THE MERGER - Conditions to the Merger".

STOCK OPTION AGREEMENT

         As an inducement to USBN to enter into the Merger Agreement, BFC has
granted USBN an option to purchase authorized but unissued shares of BFC on the
occurrence of certain events. The option, if exercised, would allow USBN to
acquire a number of shares equal to 19.9% of the outstanding shares of BFC
common stock, at $45.00 per share. See "THE MERGER - BFC Stock Option". A copy
of the Stock Option Agreement is attached to this Prospectus/Joint Proxy
Statement as APPENDIX D.



                                       4

<PAGE>   15


AMENDMENT OR TERMINATION OF THE MERGER AGREEMENT

         The Merger Agreement may be amended at any time prior to the closing,
if both the USBN and BFC boards of directors approve. However, if any amendment
would reduce or change the form of consideration that BFC stockholders will
receive, the BFC stockholders will have to approve that change.

         The Merger Agreement may be terminated, and the Merger abandoned, at
any time (even after approval by USBN's and BFC's stockholders) if both the USBN
and BFC boards of directors agree to do so. Also, in certain circumstances
either one of USBN's or BFC's board of directors may terminate the Merger
Agreement, without the other board's consent. This would be the case, for
example, if the Merger has not occurred by June 30, 1999. In certain
circumstances involving the termination of the Merger, either USBN or BFC may be
required to pay the other party a termination fee of $500,000. See "THE MERGER -
Amendment or Termination of the Merger Agreement."

OWNERSHIP OF USBN AFTER THE MERGER

         Assuming that no BFC stockholders exercise their dissenters' rights,
and without taking into account any possible upward adjustment based on BFC's
1999 net income, the former stockholders of BFC will own approximately ___% of
the outstanding USBN stock after the Merger.

USBN AND BFC DIRECTORS AND OFFICERS AFTER THE MERGER

         After the Merger, the management and board of directors of the Bank
will remain unchanged, except that two additional persons, to be designated by
USBN, will join the Bank's board of directors. They will serve until the next
annual stockholders' meeting of the Bank.

         After the Merger, three current directors of BFC will join the USBN
board of directors. See "THE MERGER - Directors and Executive Officers After the
Merger."

ACCOUNTING TREATMENT OF THE MERGER

         We expect the Merger to qualify as a "pooling of interests," which
means that, for accounting and financial reporting purposes, USBN and BFC will
be treated as if they had always been one company. See "THE MERGER - Accounting
Treatment of the Merger."

DISSENTERS' RIGHTS OF APPRAISAL

         BFC stockholders are entitled to dissent from the Merger if they follow
certain procedures, and if the Merger occurs. If such persons properly dissent,
they will have the right to obtain payment of the fair value of their BFC common
stock in cash, as provided by Washington law. USBN stockholders are not entitled
to dissenters' rights.

         If a BFC stockholder fails to follow exactly the procedures specified
in the applicable Washington law, he or she will lose his or her rights to
dissent. If you wish to dissent, you should carefully read "THE MERGER -
Dissenters' Rights of Appraisal" and the copy of the applicable Washington
statute, which is attached as APPENDIX E.



                                       5

<PAGE>   16


INTERESTS OF CERTAIN PERSONS IN THE MERGER

         Certain members of BFC's management may be deemed to have interests in
the Merger in addition to their interests as stockholders of BFC generally. See
"THE MERGER - Interests of Certain Persons in the Merger."

COMPARISON OF STOCKHOLDERS' RIGHTS

         BFC stockholders' rights are governed by BFC's Articles of
Incorporation and Bylaws. After the Merger such persons will be USBN
stockholders, and their rights will be governed by USBN's Articles of
Incorporation and Bylaws. See "COMPARISON OF CERTAIN RIGHTS OF HOLDERS OF USBN
AND BFC COMMON STOCK" for a discussion of the major differences in the rights of
the stockholders of the two companies.

TRADING MARKETS

         USBN's common stock is quoted on the Nasdaq National Market ("Nasdaq")
under the symbol "USBN." USBN's common stock is registered as a class with the
SEC under the Securities Exchange Act of 1934, as amended ("1934 Act"). See
"STOCK PRICE AND DIVIDEND INFORMATION." Accordingly, USBN is required to file
periodic reports with the SEC and to make information about USBN available to
its stockholders and the public. See "WHERE YOU CAN FIND MORE INFORMATION."

         BFC is not subject to the information and reporting requirements of the
1934 Act. BFC's common stock is not actively traded, and is not listed on any
market system. See "STOCK PRICE AND DIVIDEND INFORMATION."

                            BFC DIRECTOR CONFIRMATION

         At the BFC special stockholders meeting, BFC stockholders will also
vote on a proposal to confirm the composition of the membership of the BFC board
of directors. BFC directors have historically been elected on a "staggered"
basis. This means the board is divided into three classes, with each class being
elected on a rotating basis for a term of three years. BFC's Articles of
Incorporation do not specifically provide for a staggered board of directors. In
order to remedy the discrepancy and to eliminate possible ambiguity regarding
the composition of the BFC board, BFC stockholders will vote on a proposal to
confirm the present composition of the board of directors and the actions taken
by the board. See "DIRECTOR CONFIRMATION."

         Approval of the proposal to confirm the BFC board and its actions taken
as a board of directors requires the affirmative vote of a majority of the votes
cast at the BFC special stockholders meeting. See "BFC SPECIAL STOCKHOLDERS
MEETING."



                                       6


<PAGE>   17



                      STOCK PRICE AND DIVIDEND INFORMATION

USBN

         The USBN common stock is listed on Nasdaq under the symbol "USBN." The
respective high and low sale prices of the USBN common stock for the periods
indicated are shown below. The prices below do not include retail mark-ups,
mark-downs or commissions, and may not represent actual transactions. The per
share information has been adjusted retroactively for all stock dividends and
split-ups previously issued. As of November 30, 1998, there were approximately
1,250 holders of record of the USBN common stock.

<TABLE>
<CAPTION>
                                    YEAR ENDING DECEMBER 31, 1998                      YEAR ENDED DECEMBER 31, 1997
                           -------------------------------------------       --------------------------------------------
                                                             Cash                                              Cash
                                                             Dividends                                         Dividends
                           Market Price                      Declared        Market Price                      Declared
                           ------------                      ---------       ------------                      ----------
                                High              Low                             High              Low
                               ------           ------                           -----            ------
<S>                            <C>              <C>                <C>           <C>              <C>                <C>
1st Quarter                    $22.94           $17.16             $0            $13.86           $11.57             $0
2nd Quarter                     23.00            20.00              0             13.18            11.59              0
3rd Quarter                     21.63            16.00              0             16.94            12.62              0
4th Quarter (1)                 18.50            14.00              0             19.09            16.14              0
</TABLE>

(1)  Through November 30, 1998.


BFC

         No broker makes a market in BFC common stock, and trading has not
otherwise been extensive. The trades that have occurred cannot be characterized
as amounting to an established public trading market. BFC common stock is traded
by individuals on a personal basis and not listed on any exchange or traded on
the over-the-counter market, and the prices reported reflect only the
transactions known to management. Due to the limited information available, the
following data may not accurately reflect the actual market value of BFC common
stock. The following data includes trades between individual investors, as
reported to BFC as its own transfer agent.



<TABLE>
<CAPTION>
                                                                   Stock Prices
                                           NO. OF             ------------------------
CALENDAR YEAR QUARTER                      SHARES TRADED       HIGH             LOW
---------------------                      -------------      ------           -------
<S>           <C>                                   <C>       <C>              <C>   
First Quarter 1997                                  76        $42.00           $38.00
Second Quarter 1997                                 32        $43.75           $43.75
Third Quarter 1997                                   0            --               --
Fourth Quarter 1997                                330        $43.75           $42.00
First Quarter 1998                                 238        $50.00           $44.00
Second Quarter 1998                                  0            --               --
Third Quarter 1998                                   0            --               --
Fourth Quarter 1998 (through 11/30/98)               0            --               --
</TABLE>

         BFC did not declare dividends on its common stock in 1998 or 1997.



                                       7

<PAGE>   18


RECENT STOCK PRICE DATA

         The following table sets forth the closing price per share of USBN
common stock, as reported on Nasdaq, and of BFC common stock, in addition to the
equivalent per share price for BFC common stock, on November 10, 1998 (the last
full trading day prior to the public announcement of the execution of the Merger
Agreement) and on December __, 1998, the most recent date for which it is
practicable to obtain market price data prior to the printing of this
Prospectus/Joint Proxy Statement. Holders of BFC common stock are urged to
obtain current market quotations for shares of USBN common stock.


<TABLE>
<CAPTION>
CLOSING PRICE PER SHARE:                   November 10, 1998       December __, 1998
------------------------                   -----------------       -----------------
<S>                                             <C>                        <C>
         USBN Common Stock                      $16.56                     $
         BFC Common Stock(1)                    $50.00                     $
         BFC Equivalent Pro Forma(2)            $77.83                     $
</TABLE>

-------------------

(1)    There are no publicly available quotations of BFC common stock, and the
       market prices per share as of such dates (quoted above), represent the
       purchase prices known to BFC's management to have been paid for the BFC
       common stock in the last transaction prior to such dates.

(2)    Giving effect to the Merger and computed by multiplying the closing price
       per share of USBN common stock by an assumed exchange ratio of 4.7 shares
       of USBN common stock for one share of BFC common stock. The assumed
       exchange ration of 4.7 does not take into account any possible upward
       adjustment based on BFC's 1999 net income. See "THE MERGER - Basic Terms
       of the Merger."



                                       8



<PAGE>   19



                        EQUIVALENT PER COMMON SHARE DATA

         The following table presents unaudited selected per common share data
for USBN on a historical and pro forma combined basis and for BFC, on a
historical and pro forma equivalent basis, after giving effect to the Merger on
a pooling of interests basis. For a description of the pooling of interests
method of accounting with respect to the Merger see "THE MERGER -- Accounting
Treatment of the Merger." The pro forma combined financial data are not
necessarily indicative of actual or future operating results or the financial
position that would have occurred had the Merger become effective prior to the
period indicated or will occur upon consummation of the Merger. This data should
be read in conjunction with the financial statements and other financial data
with respect to USBN and BFC included elsewhere in this Prospectus/Joint Proxy
Statement or incorporated herein by reference. The data is not necessarily
indicative of the results of future operations of the combined entity or the
actual results that could have occurred had the Merger become effective prior to
the periods indicated. The table assumes an exchange ratio of 4.7 shares of USBN
common stock for one share of BFC common stock; the actual exchange ratio cannot
be determined at this time and will not be calculable until shortly before the
Merger. See "THE MERGER -- Basic Terms of the Merger."

<TABLE>
<CAPTION>
                                                                   PRO FORMA    PRO FORMA
                                              USBN        BFC       COMBINED    EQUIVALENT
                                             ------     ------     ---------    ----------
                                             (2)(3)                  (2)(4)       (2)(4)
<S>                                            <C>      <C>         <C>        <C>      
BOOK VALUE (1) AS OF:
   September 30, 1998                        $ 9.01     $32.18      $ 8.24       $38.73
   December 31, 1997                         $ 8.07      27.30      $ 7.25       $34.08
BASIC EARNINGS PER SHARE (5):
   Nine months ended September 30, 1998      $ 0.94     $ 4.57      $  .92       $ 4.32
   Nine months ended September 30, 1997      $ 0.88     $ 4.69      $  .99       $ 4.65
   Year Ended December 31, 1997              $ 1.17     $ 5.46      $ 1.23       $ 5.78
   Year Ended December 31, 1996              $  .77     $ 5.61      $  .99       $ 4.65
   Year Ended December 31, 1995              $ 1.04     $ 4.18      $ 1.06       $ 4.98
DILUTED EARNINGS PER SHARE (5):
   Nine months ended September 30, 1998      $ 0.92     $ 4.50      $ 0.91       $ 4.28
   Nine months ended September 30, 1997      $ 0.88     $ 4.59      $ 0.98       $ 4.61
   Year Ended December 31, 1997              $ 1.16     $ 5.33      $ 1.22       $ 5.73
   Year Ended December 31, 1996              $  .76     $ 5.48      $  .98       $ 4.61
   Year Ended December 31, 1995              $ 1.04     $ 4.07      $ 1.06       $ 4.98
CASH DIVIDENDS DECLARED PER SHARE:
   Nine months ended September 30, 1998      $    0     $    0      $    0       $    0
   Nine months ended September 30, 1997      $    0     $    0      $    0       $    0
   Year Ended December 31, 1997              $    0     $    0      $    0       $    0
   Year Ended December 31, 1996              $    0     $ 8.24      $  .44       $ 2.07
   Year Ended December 31, 1995              $    0     $    0      $    0       $    0
</TABLE>

---------------

(1)    Book value per share is calculated by dividing the total actual
       historical and pro forma equity as of the date indicated by the actual
       historical and pro forma number of shares outstanding as of the same
       date.

(2)    Effective July 20, 1998, USBN acquired Grant National Bank ("GNB"). The
       pooling of interests method of accounting was used for the transaction.
       Accordingly, all prior period USBN financial information has been
       restated to reflect the acquisition of GNB. Effective October 1, 1997,
       USBN acquired Bank of Pullman. The purchase method of accounting was used
       for the transaction. Accordingly, prior period financial statements for
       USBN have not been restated to reflect combined accounts of Bank of
       Pullman. 



                                       9

<PAGE>   20


       The pro forma combined and equivalent amounts include the accounts of
       Bank of Pullman since October 1, 1997.

(3)    In 1997, USBN received a recovery from its insurance provider related to
       a theft by a former employee. After income taxes the recovery improved
       basic earnings per share $.12 per share. In 1996, USBN discovered the
       theft which reduced basic earnings per share $.13 per share. Without the
       impact of the recovery and loss, annual basic earnings per share would
       have been $1.05 for 1997 and $.90 for 1996. In 1995, USBN received a
       death benefit from its insurance policy related to the death of a key
       employee. Without the impact of the death benefit, annual basic earnings
       per share would have been $.84 for 1995. See USBN's 1997 Annual Report on
       Form 10-K for further discussion of these matters.

(4)    The pro forma combined book value per share of USBN common stock is based
       upon the historical total combined stockholders' equity for USBN and BFC
       divided by the total pro forma common shares of the combined entities
       assuming conversion of the outstanding BFC common stock at an assumed
       ratio (made for purpose of this calculation only) of 4.7. The assumed
       exchange ratio is based upon total consideration of $33.3 million and
       1,850,000 shares of USBN common stock issued to BFC stockholders, who
       hold 393,300 shares, including options, of BFC common stock. This
       assumption is made solely for the purpose of calculating the pro forma
       data and is not intended to be a representation or approximation of the
       actual exchange ratio. USBN had 4,533,284 shares of common stock
       outstanding as of September 30, 1998. The pro forma equivalent amounts
       represent the pro forma combined amounts multiplied by the assumed
       exchange ratio of 4.7.

(5)    Basic and diluted earnings per share is calculated by dividing the total
       actual historical and pro forma net income for the periods ended by the
       actual historical and pro forma weighted average number of shares of
       common stock and common stock equivalents for the period indicated. The
       pro forma equivalent net income per share of BFC common stock represents
       the pro forma combined net income per share multiplied by the assumed
       exchange ratio described in note (4) above. Earnings per share is
       retroactively adjusted for stock dividends and split ups.



                                       10

<PAGE>   21



                       SELECTED HISTORICAL FINANCIAL DATA

         The tables on the following pages set forth, for the respective periods
specified, selected unaudited pro forma combined financial data giving effect to
the Merger on a "pooling of interests" basis, and selected unaudited historical
financial data for each of USBN and BFC. The pro forma combined financial data
are presented as though the Merger had been consummated at the beginning of the
period set forth; however, such data is not necessarily indicative of actual or
future operating results or the financial position that would have occurred or
will occur on the consummation of the Merger. The data has been derived in part
from, and should be read in conjunction with, the consolidated financial
statements and notes thereto and other financial information with respect to
USBN and BFC set forth elsewhere in this Prospectus/Joint Proxy Statement or
incorporated into this Prospectus/Joint Proxy Statement by reference, and such
data are qualified in their entirety by reference thereto.

         All adjustments that the respective managements of USBN and BFC believe
to be necessary for a fair presentation of the data have been included. The
September 30, 1997 and 1998 ratios have been annualized where necessary. Dollar
amounts are in thousands, except per share data.

PRO FORMA USBN & BFC

<TABLE>
<CAPTION>
                                           AT OR FOR THE  
                                         NINE MONTHS ENDED
                                           SEPTEMBER 30,                       AT OR FOR THE YEAR ENDED DECEMBER 31,
                                     ------------------------    ------------------------------------------------------------------
                                        1998          1997          1997          1996          1995          1994          1993
<S>                                  <C>           <C>           <C>           <C>           <C>           <C>           <C>       
Net interest income                  $   19,444    $   15,473    $   21,697    $   18,947    $   15,409    $   12,854    $   10,553
Provision for loan losses                   424           605         1,055         1,021           379           765           519
Noninterest income                        4,042         3,772         4,832         3,986         4,622         3,006         3,003
Noninterest expense                      14,462        10,370        14,905        13,956        12,151        10,262         9,357
Income before income tax expense          8,600         8,270        10,569         7,956         7,501         4,833         3,679
Income tax expense                        2,705         2,614         3,346         2,539         2,004         1,526         1,126
Net income                                5,895         5,656         7,223         5,417         5,497         3,307         2,553
Basic earnings per common share      $     0.92    $     0.99    $     1.23    $     0.99    $     1.06    $     0.74    $     0.60
Diluted earnings per common share    $     0.91    $     0.98    $     1.22    $     0.98    $     1.06    $     0.74    $     0.60
Return on average assets                   1.61%         2.03%         1.82%         1.63%         1.97%         1.39%         1.17%
Return on average equity                  16.03%        18.47%        17.17%        13.52%        18.78%        17.53%        16.97%
Assets                               $  508,751    $  414,823    $  486,778    $  353,256    $  296,406    $  258,488    $  215,152
Securities                               76,680        78,332       102,964        47,519        49,758        51,235        46,866
Loans                                   356,254       281,645       317,852       256,287       211,321       181,866       140,110
Allowance for loan losses                 3,670         2,712         3,869         2,906         2,154         2,000         1,412
Allowance for loan losses to loans         1.03%         0.96%         1.22%         1.13%         1.02%         1.10%         1.01%
percentage
Deposits                                445,001       358,134       425,094       305,368       256,699       229,375       195,413
Borrowings                                5,851         8,517        11,284         3,242           767         6,120         1,658
Stockholders' equity                     52,570        44,141        46,196        38,507        35,778        21,127        16,296
Equity to assets ratio                    10.33%        10.64%         9.49%        10.90%        12.07%         8.17%         7.57%
Book value per common share          $     8.24    $     6.93    $     7.25    $     6.05    $     5.63    $     4.53    $     3.86
Number of common shares outstanding   6,383,284     6,370,882     6,370,882     6,368,682     6,349,661     4,665,946     4,226,904
Weighted average shares outstanding   6,374,262     6,369,794     6,370,068     6,360,918     5,759,609     4,467,159     4,226,904
</TABLE>



                                       11


<PAGE>   22



                     USBN SELECTED HISTORICAL FINANCIAL DATA

<TABLE>
<CAPTION>
                                            AT OR FOR THE
                                          NINE MONTHS ENDED           
                                            SEPTEMBER 30,                      AT OR FOR THE YEAR ENDED DECEMBER 31,     
                                      ------------------------    -----------------------------------------------------------------
                                         1998          1997          1997          1996          1995          1994         1993
<S>                                   <C>           <C>           <C>           <C>           <C>           <C>          <C>       
Net interest income                   $   15,353    $   11,649    $   16,565    $   14,114    $   11,347    $    9,129   $    7,179
Provision for loan losses                    324           548           752         1,021           317           585          191
Noninterest income                         3,303         3,172         3,957         3,206         3,970         2,398        2,339
Noninterest expense                       12,081         8,311        12,014        11,189         9,433         7,557        7,032
Income before income tax expense           6,251         5,962         7,756         5,110         5,567         3,385        2,294
Income tax expense                         2,015         1,966         2,464         1,656         1,489         1,143          746
Net income                                 4,236         3,996         5,292         3,454         4,078         2,242        1,548
Basic earnings per common share       $     0.94    $     0.88    $     1.17    $     0.77    $     1.04    $     0.86   $     0.65
Diluted earnings per common share     $     0.92    $     0.88    $     1.16    $     0.76    $     1.04    $     0.86   $     0.65
Return on average assets                    1.46%         1.94%         1.77%         1.43%         2.03%         1.33%        0.95%
Return on average equity                   14.67%        16.34%        15.83%        11.74%        18.66%        17.68%       15.51%
Assets                                $  404,667    $  313,956    $  384,269    $  259,744    $  214,563    $  185,524   $  150,759
Securities                                50,056        49,913        73,583        20,495        27,527        29,263       28,870
Loans                                    285,044       214,826       250,580       196,032       157,651       136,193      102,339
Allowance for loan losses                  2,805         2,133         2,865         2,295         1,594         1,432        1,002
Allowance for loan losses to loans          0.98%         0.99%         1.14%         1.17%         1.01%         1.05%        0.98%
percentage
Deposits                                 354,829       271,623       337,804       222,998       183,941       164,680      136,906
Borrowings                                 5,174         4,372         6,989         3,242           767         5,145        1,658
Stockholders' equity                      40,849        34,954        36,485        31,012        27,568        14,494       10,780
Equity to assets ratio                     10.09%        11.13%         9.49%        11.94%        12.85%         7.81%        7.15%
Book value per common share           $     9.01    $     7.73    $     8.07    $     6.86    $     6.13    $     5.15   $     4.54
Number of common shares outstanding    4,533,284     4,520,882     4,520,882     4,518,682     4,499,661     2,815,946    2,376,904
Weighted average shares outstanding    4,524,262     4,519,794     4,520,068     4,510,918     3,909,609     2,617,159    2,376,904
</TABLE>



                                       12


<PAGE>   23



                     BFC SELECTED HISTORICAL FINANCIAL DATA

<TABLE>
<CAPTION>
                                                 AT OR FOR THE
                                               NINE MONTHS ENDED             
                                                 SEPTEMBER 30,               AT OR FOR THE YEAR ENDED DECEMBER 31,   
                                             --------------------    --------------------------------------------------------
($ in thousands, except per share amounts)     1998        1997        1997        1996        1995        1994        1993
<S>                                          <C>         <C>         <C>         <C>         <C>         <C>         <C>     
Net interest income                          $  4,091    $  3,824    $  5,132    $  4,833    $  4,062    $  3,725    $  3,374
Provision for loan losses                         100          57         303          62         180         328
Noninterest income                                739         600         875         780         652         608         664
Noninterest expense                             2,381       2,059       2,891       2,767       2,718       2,705       2,325
Income before income tax expense                2,349       2,308       2,813       2,846       1,934       1,448       1,385
Income tax expense                                690         648         882         883         515         383         380
Net income                                      1,659       1,660       1,931       1,963       1,419       1,065       1,005
Basic earnings per common share              $   5.46    $   4.69    $   4.57    $   5.61    $   4.18    $   3.19    $   3.03
Diluted earnings per common share                                    $   5.33    $   4.59    $   4.50    $   5.48    $   4.07
Return on average assets                         2.20%       2.32%       2.00%       2.18%       1.82%       1.55%       1.67%
Return on average equity                        20.75%      26.56%      22.22%      20.87%      19.17%      17.21%      19.81%
Assets                                       $104,084    $100,867    $102,509    $ 93,512    $ 81,843    $ 72,964    $ 64,393
Securities                                     26,624      28,419      29,381      27,024      22,231      21,972      17,996
Loans                                          71,210      66,819      67,272      60,255      53,670      45,673      37,771
Allowance for loan losses                         865         579       1,004         611         560         568         410
Allowance for loan losses to loans               1.21%       0.87%       1.49%       1.01%       1.04%       1.24%       1.09%
percentage
Deposits                                       90,172      86,511      87,290      82,370      72,758      64,695      58,507
Borrowings                                        677       4,145       4,295           0           0         975           0
Stockholders' equity                           11,721       9,187       9,711       7,495       8,210       6,633       5,516
Equity to assets ratio                          11.26%       9.11%       9.47%       8.02%      10.03%       9.09%       8.57%
Book value per common share                  $  32.18    $  25.83    $  27.30    $  21.43    $  24.17    $  19.80    $  16.82
Number of common shares outstanding           364,281     355,684     355,684     349,723     339,700     335,018     327,940
Weighted average shares outstanding           363,280     353,616     353,974     349,423     339,572     333,856     331,683
</TABLE>



                                       13


<PAGE>   24



                        USBN SPECIAL STOCKHOLDER MEETING

DATE, TIME AND PLACE

         The USBN special meeting will be held on January ___, 1999 at _________
__.m., local time, at _____________________________, Spokane, Washington.

PURPOSE

         The purposes of the USBN special meeting are as follows: (i) to
consider and vote upon approval of the Merger Agreement and (ii) to act upon
other matters, if any, that may properly come before the USBN special meeting.

RECORD DATE; SHARES OUTSTANDING AND ENTITLED TO VOTE

         The USBN board of directors has fixed 5:00 p.m. on December 21, 1998 as
the USBN record date for determining the holders of shares of USBN common stock
entitled to notice of and to vote at the USBN special meeting. At the close of
business on the USBN record date, there were ________ shares of USBN common
stock issued and outstanding held by approximately _____ holders of record.
Holders of record of USBN common stock on the USBN record date are entitled to
one vote per share.

VOTE REQUIRED

         The affirmative vote of two-thirds of all shares of USBN common stock
outstanding on the USBN record date is required to approve the Merger Agreement.
The presence of a majority of the outstanding shares of USBN common stock in
person or by proxy is necessary to constitute a quorum of stockholders for the
USBN special meeting. For this purpose, abstentions and broker non-votes (i.e.
proxies from brokers or nominees indicating that such person has not received
instructions from the beneficial owners or other persons entitled to vote shares
as to a matter with respect to which the broker or nominees do not have
discretionary power to vote) are counted in determining the shares present at a
meeting. For voting purposes, however, only shares affirmatively voted for the
approval of the Merger Agreement, and neither abstentions nor broker non-votes,
will be counted as favorable votes in determining whether the Merger Agreement
is approved by the holders of USBN common stock. As a consequence, abstentions
and broker non-votes will have the same effect as votes against approval of the
Merger Agreement.

VOTING, SOLICITATION, AND REVOCATION OF PROXIES

         If the enclosed proxy is duly executed and received in time for the
USBN special meeting, it will be voted in accordance with the instructions
given. If no instruction is given, it is the intention of the persons named in
the proxy to vote the shares represented by the proxy FOR the approval of the
Merger Agreement and in the proxy's discretion on any other matter coming before
the meeting, unless otherwise directed by the proxy. Any proxy given by a
stockholder may be revoked before its exercise by written notice to the
Secretary of USBN, or by a subsequently dated proxy, or in open meeting before
the stockholder vote is taken. The shares represented by properly executed,
unrevoked proxies, will be voted in accordance with the instructions in the
proxy.

         The proxy for the USBN special meeting is being solicited on behalf of
the USBN board of directors. USBN will bear the cost of solicitation of proxies
from its stockholders. In addition to using the mails, proxies may be solicited
by personal interview, telephone, and wire. Banks, brokerage houses, other
institutions, nominees, and fiduciaries will be requested to forward their proxy
soliciting material to their principals and 



                                       14

<PAGE>   25


obtain authorization for the execution of the proxies. Officers and other
employees of USBN may solicit proxies personally. USBN does not expect to pay
any compensation for the solicitation of proxies, but will, upon request, pay
the standard charges and expenses of banks, brokerage houses, other
institutions, nominees, and fiduciaries for forwarding proxy materials to and
obtaining proxies from their principals.

                         BFC SPECIAL STOCKHOLDER MEETING

DATE, TIME AND PLACE

         The BFC special meeting will be held on January ___, 1999 at ______
__.m., local time, at _____________________________, Walla Walla, Washington.

PURPOSE

         The purposes of the BFC special meeting are as follows: (i) to consider
and vote upon approval of the Merger Agreement, (ii) to consider and vote upon
approval of the Director Confirmation, and (iii) to act upon other matters, if
any, that may properly come before the BFC special meeting. At the time of the
BFC special meeting, the precise number of shares of USBN common stock to be
received for each share of BFC common stock will not be known, as the exchange
ratio may be adjusted (but only upwards) prior to the Merger effective date See
"THE MERGER -- Basic Terms of the Merger."

         With respect to the BFC stockholder vote on the Director Confirmation,
see "DIRECTOR CONFIRMATION."

RECORD DATE; SHARES OUTSTANDING AND ENTITLED TO VOTE

         The BFC board of directors has fixed 5:00 p.m. on _____________, 199__
as the BFC record date for determining the holders of shares of BFC common stock
entitled to notice of and to vote at the BFC special meeting. At the close of
business on the BFC record date, there were _________ shares of BFC common stock
issued and outstanding held by approximately ______ holders of record. Holders
of record of BFC common stock on the BFC record date are entitled to one vote
per share and are also entitled to exercise dissenters' rights under Appraisal
Laws if certain procedures are followed. See "THE MERGER -- Dissenters' Rights
of Appraisal" and APPENDIX E.

VOTE REQUIRED

         The affirmative vote of two-thirds of all shares of BFC common stock
outstanding on the BFC record date is required to approve the Merger Agreement.
The affirmative vote of a majority of all votes cast at the BFC Special
Stockholder Meeting is required to approve the Director Confirmation. The
presence of a majority of the outstanding shares of BFC common stock in person
or by proxy is necessary to constitute a quorum of stockholders for the BFC
special meeting. For this purpose, abstentions and broker non-votes (i.e.
proxies from brokers or nominees indicating that such person has not received
instructions from the beneficial owners or other persons entitled to vote shares
as to a matter with respect to which the broker or nominees do not have
discretionary power to vote) are counted in determining the shares present at a
meeting. For voting purposes, however, only shares affirmatively voted for the
approval of the Merger Agreement, and neither abstentions nor broker non-votes,
will be counted as favorable votes in determining whether the Merger Agreement
is approved by the holders of BFC common stock. As a consequence, abstentions
and broker non-votes will have the same effect as votes against approval of the
Merger Agreement.



                                       15

<PAGE>   26


         As of the BFC record date, directors and executive officers of BFC, and
their affiliates, owned and were entitled to vote _______ shares at the BFC
special meeting, representing approximately _____% of the outstanding shares of
BFC common stock. See "MANAGEMENT OF BFC -- Security Ownership of Management and
Certain Beneficial Owners." Each director of BFC has agreed to vote all shares
of BFC common stock held or controlled by him or her (a total of ________ shares
or approximately ____% of the shares outstanding), in favor of approval of the
Merger.

VOTING, SOLICITATION, AND REVOCATION OF PROXIES

         If the enclosed proxy is duly executed and received in time for the BFC
special meeting, it will be voted in accordance with the instructions given. If
no instruction is given, it is the intention of the persons named in the proxy
to vote the shares represented by the proxy FOR the approval of the Merger
Agreement and the Director Confirmation and in the proxy's discretion on any
other matter coming before the meeting, unless otherwise directed by the proxy.
Any proxy given by a stockholder may be revoked before its exercise by written
notice to the Secretary of BFC, or by a subsequently dated proxy, or in open
meeting before the stockholder vote is taken. The shares represented by properly
executed, unrevoked proxies, will be voted in accordance with the instructions
in the proxy.

         The proxy for the BFC special meeting is being solicited on behalf of
the BFC board of directors. BFC will bear the cost of solicitation of proxies
from its stockholders. In addition to using the mails, proxies may be solicited
by personal interview, telephone, and wire. Banks, brokerage houses, other
institutions, nominees, and fiduciaries will be requested to forward their proxy
soliciting material to their principals and obtain authorization for the
execution of the proxies. Officers and other employees of BFC may solicit
proxies personally. BFC does not expect to pay any compensation for the
solicitation of proxies, but will, upon request, pay the standard charges and
expenses of banks, brokerage houses, other institutions, nominees, and
fiduciaries for forwarding proxy materials to and obtaining Proxies from their
principals.

                    BACKGROUND OF AND REASONS FOR THE MERGER

BACKGROUND OF THE MERGER

         In June, 1998, BFC received an unsolicited, non-binding indication of
interest to acquire BFC and its subsidiary, the Bank. The board of directors of
BFC considered the proposal and determined that if a firm offer was received
within the parameters proposed by the indication of interest, it would be in the
best interests of BFC stockholders to consider such a proposal.

         Following this meeting, Wes E. Colley, President and Chief Executive
Officer of BFC, was authorized to formally engage Columbia Financial Advisors,
Inc. ("CFA"), to contact the original inquiror and several other regional banks
(including USBN) which were most likely to be interested in, and financially and
otherwise capable of, engaging in a business combination transaction with BFC.
CFA contacted such companies and several expressed interest in considering a
strategic business combination transaction with BFC (the "Interested Parties").
Each of the Interested Parties received a package of financial information on
BFC and was required to sign a Confidentiality Agreement.

         USBN received its financial packet from CFA on August 17, 1998. After a
review of the information provided, a presentation was made to the USBN board of
directors by management on September 22, recommending making a proposal to BFC.
The USBN board of directors acted upon that recommendation and a formal offer
was tendered on September 30 to CFA.



                                       16

<PAGE>   27


         As offers were received from Interested Parties, they were analyzed by
the BFC board and senior management of BFC, together with CFA. On October 6,
1998, at a special meeting, the BFC board decided to proceed with discussions
with two of the Interested Parties. Management of USBN and BFC subsequently met
to discuss USBN's original indication of interest. Revised indications of
interest were provided by USBN and by the other Interested Party selected by
BFC. These revised indications of interests were reviewed at a special meeting
of the Board held on October 13, 1998. After considering the two offers
carefully, the board elected to accept the USBN offer, subject to clarification
of some of the terms. The parties and their respective legal and financial
advisors then discussed the terms of the proposed transaction and began the
process of scheduling and conducting due diligence and drafting and negotiating
definitive agreements reflecting the terms of the proposed transaction.

USBN'S REASONS FOR THE MERGER

         At a special meeting on November 10, 1998 the USBN board of directors
determined that the Merger Agreement is fair to and in the best interests of
USBN and its stockholders. In reaching that conclusion, USBN determined that the
Merger would advance USBN's strategic plan of growing its franchise through
internal and external opportunities. The USBN board of directors determined that
the Merger would allow it to increase its market share and presence in the
Eastern Washington market and continue its philosophy of expanding its banking
franchise through acquisitions. The USBN board of directors believes that the
Merger will also immediately have a positive impact on USBN's financial
condition and statement of operations. In addition, USBN believes that the
Merger will enhance USBN's prospects for growth in the Inland Northwest market,
as well as serve as a platform for possible continued acquisition opportunities
in the Inland Northwest.

         USBN believes that the Merger will combine financially sound
institutions with complementary businesses and strategies, thereby creating a
stronger combined organization with greater size, flexibility, efficiency, and
profitability. In addition, USBN believes that USBN and the Bank each bring
certain strengths that will augment that others' operations. The USBN board of
directors believes that (i) each institution is currently well managed, (ii)
USBN and the Bank have compatible management philosophies and strategic
objectives, (iii) the combined entity will be able to realize the benefits of
complimentary strengths at both organizations, (iv) the Merger will allow for an
increased presence in the key Eastern Washington market of Walla Walla and
Columbia Counties; and (v) the string capitalization of the combined entity will
allow it to take advantage of possible future acquisition opportunities. The
USBN board also believes that the Merger will further allow it to compete
effectively in the rapidly changing market place of banking and financial
services and to take advantage of opportunities for growth and diversification
in Eastern Washington.

         In reaching its determination to approve the Merger Agreement and
recommend the approval of the Merger to USBN stockholders, the USBN board of
directors considered a variety of factors, although it did not assign any
relative or specific weights to the factors considered. The factors considered
included the following:

         -        The financial condition, results of operation, and business
                  operations and prospects of BFC and the Bank;

         -        The current banking industry environment, including the rapid
                  consolidation and the need to effectively and proactively
                  position USBN competitively;

         -        The USBN board's belief that the acquisition of BFC will
                  expand USBN's franchise family of community banks and would be
                  a logical extension for USBN into other communities in the
                  Inland Northwest market;



                                       17

<PAGE>   28


         -        The USBN board's evaluation of the financial terms of the
                  Merger and its effect on the stockholders of USBN and the USBN
                  board's belief, supported by the advice of USBN's investment
                  advisor, that such terms are fair to USBN and its
                  stockholders;

         -        The prospect that the Merger will allow for revenue
                  enhancement and operating synergies, as well as various
                  cross-selling opportunities;

         -        The USBN board's belief that the Merger will be accretive to
                  USBN's earnings and book value per share;

         -        The USBN board's belief that the merger will diversify USBN's
                  loan portfolio and deposit mix by geography and product types;

         -        The USBN board's judgment that BFC and the Bank are
                  well-managed institutions and will be superior merger partners
                  as a result of the similarities of the institutions in culture
                  and commitment to the Eastern Washington market;

         -        The USBN board's belief that the Merger will advance USBN's
                  external growth strategy of acquiring profitable, well-managed
                  institutions and further promote USBN as a consolidator of
                  regionally-based banks;

         -        the USBN board's belief that the Merger will increase USBN's
                  market capitalization and the liquidity of it shares;

         -        Evaluation of the Merger and its effect on USBN, and the USBN
                  board's belief that the financial terms are fair to USBN and
                  its stockholders, based in part on the financial presentations
                  of PCS regarding the Merger, and the expression of PCS's
                  opinion as to the fairness to USBN of the consideration to be
                  delivered by USBN in the Merger; and

         -        The USBN board's belief, after consultation with its legal
                  counsel, that the required regulatory approvals could be
                  obtained to consummate the Merger.

         The foregoing discussion of the information and factors considered by
the USBN board of directors is not intended to be exhaustive but is believed to
encompass all material factors considered by the USBN board of directors. On the
basis of the foregoing factors, the USBN board of directors concluded that the
terms of the Merger are fair to and in the best interests of USBN and its
stockholders.

RECOMMENDATION OF USBN BOARD OF DIRECTORS

         FOR THE REASONS SET FORTH ABOVE, THE USBN BOARD OF DIRECTORS HAS
APPROVED THE MERGER AGREEMENT AS ADVISABLE AND IN THE BEST INTERESTS OF USBN AND
USBN STOCKHOLDERS AND RECOMMENDS THAT USBN STOCKHOLDERS VOTE FOR APPROVAL OF THE
MERGER AGREEMENT.

OPINION OF USBN'S FINANCIAL ADVISOR

         Pacific Crest Securities ("PCS") of Portland, Oregon, was retained by
USBN to advise the board of directors as to the fairness of the consideration,
from a financial perspective, to be paid to BFC stockholders as set forth in the
Merger Agreement between USBN and BFC. PCS will receive a fee for its services,
a portion of which is contingent upon delivery of the opinion and inclusion in
materials to stockholders of USBN. PCS was not asked to, and did not, recommend
the exchange ratio formula between BFC and USBN's respective common stocks. The
exchange ratio formula was determined by USBN and BFC after arm's-length
negotiations.



                                       18

<PAGE>   29


         PCS is an investment banking firm that performs financial advisory
services. As part of its investment banking business, PCS is regularly engaged
in reviewing the fairness of financial institution acquisition transactions from
a financial perspective and in the valuation of financial institutions and other
businesses and their securities in connection with mergers, acquisitions and
other transactions. Neither PCS nor any of its affiliates has a material
financial interest in USBN or BFC.

         Under the Merger Agreement, BFC stockholders and option holders are to
receive 1,850,000 shares of USBN stock. Additional shares will be issued to
compensate BFC for any net income earned from January 1, 1999 until the Closing
of the Merger. For purposes of this analysis, the additional USBN shares earned
from the net income provision were ignored due to the assumption that the amount
will be immaterial.

         PCS reviewed certain publicly available business and financial
information relating to USBN and BFC. PCS reviewed certain other estimated
information, including financial forecasts and local market analyses, provided
by USBN, BFC and outside parties. In addition, PCS also conducted interviews
with officers of USBN and BFC as to the business and prospects of BFC. PCS also
compared certain financial data from USBN and BFC to those of similar publicly
held banks or bank holding companies. Additionally, PCS considered the financial
terms of certain other business combinations in the commercial banking industry
that have recently been effected. PCS also considered certain estimated combined
financial information of USBN and BFC. PCS did not independently verify the
accuracy and/or the completeness of the financial and other information reviewed
in rendering its opinion. PCS did not, and was not requested to, solicit third
party indications of interest in acquiring any or all of the assets of BFC.

         Based upon the transaction terms and a USBN stock price as of the date
of PCS's opinion of $16.88, USBN will pay to BFC stockholders consideration
equating to approximately 2.6 times BFC's book value at September 30, 1998 and
14.4 times earnings for the trailing 12 month period ended September 30, 1998.
Based upon the review conducted by PCS, the pricing for BFC in the Merger is the
range of multiples seen in recent bank acquisitions. PCS also utilized several
analyses to determine the fairness of the future economic benefits of BFC's
tangible and intangible net assets to USBN stockholders, relative to the
consideration paid. PCS's conclusion was that the terms of the Merger pursuant
to the Merger Agreement are fair, from a financial viewpoint, to the
stockholders of USBN.

         THE FULL TEXT OF THE PCS OPINION, UPDATED TO DECEMBER _, 1998, WHICH
SETS FORTH THE ASSUMPTIONS MADE, MATTERS CONSIDERED, AND LIMITS ON ITS REVIEW,
IS ATTACHED TO THIS PROSPECTUS/JOINT PROXY STATEMENT AS APPENDIX B. THE SUMMARY
OF THE PCS OPINION IN THIS PROSPECTUS/JOINT PROXY STATEMENT IS QUALIFIED IN ITS
ENTIRETY BY REFERENCE TO THE FULL TEXT OF SUCH OPINION. USBN STOCKHOLDERS ARE
URGED TO READ THE ENTIRE PCS OPINION.

BFC'S REASONS FOR THE MERGER

         At a meeting of the BFC board of directors of BFC held on November 10,
1998, Wes Colley, a representative of CFA and a representative of Keller
Rohrback, L.L.P., special legal counsel to BFC, updated the BFC board on the
events that had taken place since the prior meeting and reviewed with the board
the proposed Merger Agreement. CFA provided its opinion that the offer was fair
from a financial perspective to the stockholders of BFC. Following the
presentation, the board unanimously approved the Merger. Listed below are the
material factors the BFC board considered in reaching their decision.

         -        Confronted with changing stockholder demographics and desires,
                  the BFC board determined that combining with a larger,
                  publicly-traded company would result in improved liquidity for
                  BFC stockholders.



                                       19

<PAGE>   30


         -        Combining the management resources of USBN and BFC would
                  result in a greater depth of management.

         -        Because of USBN's size and resources, the Bank's customers
                  will benefit from more products and services and the Bank's
                  employees will also benefit from enhanced technology and
                  training, which in turn would provide substantially improved
                  career opportunities.

         -        Continuing the Bank's local operations while accessing the
                  financial, technological and human resource strength of USBN
                  would greatly enhance BFC's ability to compete in an
                  ever-changing marketplace.

         -        The board considered the financial condition and operating
                  results of USBN, and the fact that the transaction would be a
                  tax-free reorganization to the BFC stockholders.

         -        The presentation of CFA and the opinion of CFA rendered on
                  November 10, 1998, that as of such date the exchange ratio
                  pursuant to the Merger Agreement was fair from a financial
                  point of view to the holders of BFC common stock.

         -        The terms of the Merger Agreement, including: (i) a provision
                  for a fixed exchange ratio of 4.7038 shares of USBN common
                  stock for each share of BFC common stock plus additional
                  shares based upon the net income realized by BFC from January
                  1, 1999, until closing, enabling BFC stockholders to benefit
                  from any increase in the trading price of USBN common stock
                  prior to the Merger, coupled with a provision permitting BFC
                  to terminate the Merger if the Average Closing Price of USBN
                  common stock is below $12.50, thereby limiting the risk to BFC
                  stockholders to possible declines in USBN common stock; (ii)
                  an attractive premium for the holders of BFC common stock.

         -        Merging with USBN would be a better alternative than expanding
                  independently through internal growth or through acquisition.

         The BFC board did not assign any specific or relative weight to any of
the factors discussed above in their considerations.

         RECOMMENDATION OF BFC BOARD OF DIRECTORS

         FOR THE REASONS SET FORTH ABOVE, THE BFC BOARD UNANIMOUSLY APPROVED THE
MERGER AGREEMENT AS ADVISABLE AND IN THE BEST INTERESTS OF BFC AND ITS
STOCKHOLDERS AND RECOMMENDS THAT THE STOCKHOLDERS OF BFC VOTE FOR THE APPROVAL
OF THE MERGER AGREEMENT.

OPINION OF BFC'S FINANCIAL ADVISORS

         CFA has delivered a written opinion to the BFC board to the effect
that, as of the date of this Prospectus/ Joint Proxy Statement, the
consideration to be received by BFC common stockholders pursuant to the terms of
the Merger Agreement is fair to such stockholders from a financial point of
view. The exchange ratio of 4.7349 shares (based for the purposes of the
following analysis, upon the price calculation described below and an assumed
net income of $200,000 realized by BFC from January 1, 1999 until an assumed
closing date of January 31, 1999), of USBN common stock for each share of BFC
has been determined by BFC and USBN through negotiations. The CFA opinion is
directed only to the fairness, from a financial point of view, of the
consideration to be received and does not constitute a recommendation to any BFC
stockholder as to how such stockholder should vote at the BFC special meeting.
As of December ___, 1998, the price of USBN's common 



                                       20

<PAGE>   31


stock is $______ as reported in the Wall Street Journal, and the total purchase
price is an estimated $_____ per share for all of the outstanding shares of BFC.

         BFC retained CFA as its exclusive financial advisor pursuant to an
engagement letter dated July 20, 1998 in connection with the Merger. CFA is a
regionally recognized investment banking firm that is regularly engaged in the
valuation of businesses and securities in connection with mergers and
acquisitions. The BFC board selected CFA to act as BFC's exclusive financial
advisor based on CFA's experience in mergers and acquisitions and in securities
valuation generally.

         On November 10, 1998, CFA issued its opinion to the BFC board that, in
its opinion as investment bankers, the terms of the Merger as provided in the
Merger Agreement are fair, from a financial view point, to BFC, the Bank and its
stockholders. THE FULL TEXT OF THE CFA OPINION, UPDATED TO DECEMBER ____, 1998,
WHICH SETS FORTH THE ASSUMPTIONS MADE, MATTERS CONSIDERED, AND LIMITS ON ITS
REVIEW, IS ATTACHED HERETO AS APPENDIX C. THE SUMMARY OF THE CFA OPINION IN THIS
PROSPECTUS/JOINT PROXY STATEMENT IS QUALIFIED IN ITS ENTIRETY BY REFERENCE TO
THE FULL TEXT OF SUCH OPINION. BFC STOCKHOLDERS ARE URGED TO READ THE ENTIRE CFA
OPINION.

         In rendering its opinion to BFC, CFA reviewed, among other things,
historical financial data of BFC, certain internal financial data and
assumptions of BFC prepared for financial planning and budgeting purposes
furnished by the management of BFC and, to the extent publicly available, the
financial terms of certain change of control transactions involving Northwest
community banks. CFA discussed the BFC's management and financial condition,
current operating results, and business outlook for BFC. CFA also reviewed
certain publicly available information concerning USBN and certain financial and
securities data of USBN and companies deemed similar to USBN. CFA discussed with
USBN's management the financial condition, current operating results, and
business outlook for USBN and USBN's plans relating to BFC. In rendering its
opinion, CFA relied, without independent verification, on the accuracy and
completeness of all financial and other information reviewed by it and did not
attempt to verify or to make any independent evaluation or appraisal of the
assets of BFC or USBN nor was it furnished any such appraisals. BFC did not
impose any limitation on the scope of the CFA investigation in arriving at its
opinion. CFA analyzed the total Merger purchase price on a cash equivalent fair
market value basis using standard evaluation techniques (as discussed below)
including comparable sales multiples, net present value analysis, and net asset
value based on certain assumption of projected growth, earnings and dividends
and a range of discount rates from 16% to 18%.

         NET ASSET VALUE is the value of the net equity of a bank, including
every kind of property and value. This approach normally assumes the liquidation
on the date of appraisal with the recognition of the investment securities gains
or losses, real estate appreciation or depreciation, adjustments to the loan
loss reserve, discounts to the loan portfolio and changes in the net value of
other assets. As such, it is not the best evaluation approach when valuing a
going concern because it is based on historical costs and varying accounting
methods. Even if the assets and liabilities are adjusted to reflect prevailing
market prices and yields (which is often of limited accuracy due to the lack of
readily available data), it still results in a liquidation value. In addition,
since this approach fails to account for the values attributable to the going
concern such as the interrelationship among BFC's assets and liabilities,
customer relations, market presence, image and reputation, staff expertise and
depth, little weight is given by CFA to the net asset value approach to
valuation.

         MARKET VALUE is generally defined as the price, established on an
"arms-length" basis, at which knowledgeable, unrelated buyers and sellers would
agree. The "hypothetical" market value for a small bank with a thin market for
its common stock is normally determined by comparison to the average price to
stockholders equity, price to earnings, and price to total assets, adjusting for
significant differences in financial performance criteria and for any lack of
marketability or liquidity of the buyer. The market value in connection with the
evaluation of control of a bank is determined by the previous sales of small
banks in the state or region. In 



                                       21

<PAGE>   32


valuing a business enterprise, when sufficient comparable trade data are
available, the market value approach deserves greater weighting than the net
asset value approach and similar weight as the investment value approach as
discussed below.

         CFA maintains a comprehensive data base concerning prices paid for
banking institutions in the Northwest, particularly Eastern Washington and
Eastern Oregon banking institutions, during 1988 through 1998. This data base
provides comparable pricing and financial performance data for banking
institutions sold or acquired. Organized by different peer groups, these data
present medians of financial performance and purchase price levels, thereby
facilitating a valid comparative purchase price analysis. In analyzing the
transaction value of BFC, CFA has considered the market approach and has
evaluated price to stockholders equity and price to earnings multiples and the
price to total assets percentage for transactions involving Washington and
Oregon banking organizations with total assets less than $150 million that sold
for 100% common stock from January 1988 to November 1998.

         Comparable Sales Multiples. CFA calculated a "Merger
Consideration-Adjusted Book Value" for BFC's September 30, 1998 stockholders
equity and the estimated March 31, 1999 stockholders' equity adjusted for the
price to stockholders equity ratios for a sample of Northwest banking
institutions with assets of below $150 million which sold between January 1,
1992 through November 1, 1998 and a sample of Northwest banking institutions
with total assets of below $150 million which sold between January 1, 1996 and
November 1, 1998. The calculations are $61.49 and $69.99 per share,
respectively, for the September 30, 1998 stockholders' equity for the two
samples. For the estimated December 31, 1998 stockholders' equity, the
calculations are $61.86 and $70.39, respectively. For BFC's net income for the
twelve months prior to September 30, 1998, the calculations are $97.02 and
$103.84, respectively.

         Transaction Value as a Percentage of Total Assets. CFA calculated the
percentage of total assets which the transaction represents as a price level
indicator. The transaction value as a percentage of total assets facilitates a
truer price level comparison with comparable banking organizations, regardless
of the differing levels of stockholders equity and earnings. In this instance, a
transaction value of $______ per BFC share results in a transaction value as a
percentage of total assets of 29.53%. The median price as a percentage of total
assets for a sample of Northwest banking institutions with assets of below $150
million which sold between January 1, 1992 through June 1, 1998 and a sample of
Northwest banking institutions with total assets of below $150 million which
sold between January 1, 1996 and November 1, 1998 of 20.00% and 21.10%,
respectively.

         INVESTMENT VALUE is sometimes referred to as the income or earnings
value. One investment value method frequented used estimates the present value
of an institution's future earnings or cash flow which is discussed below.

         Net Present Value Analysis. The investment or earnings value of any
banking organization's stock is an estimate of the present value of future
benefits, usually earnings, dividends, or cash flow, which will accrue to the
stock. An earnings value is calculated using an annual future earning stream
over a period of time of not less than five years and the residual or terminal
value of the earnings stream after five years, using BFC's estimates of future
growth and an appropriate capitalization or discount rate. CFA's calculations
were based on an analysis of the banking industry, BFC's earnings estimates for
1998-2002, historical levels of growth and earnings, and the competitive
situation in BFC's market area. Using discount rates of 16% and 18%, acceptable
discount rates considering the risk-return relationship most investors would
demand for an investment of this type as of the valuation date, the "Net Present
Value of Future Earnings" provided a range of $72.19 to $76.77 per share.

         When the net asset value, market value and investment value approaches
are subjectively weighed, using the appraiser's experience and judgment, it is
CFA's opinion that the proposed transaction is fair, from a financial point of
view to the BFC stockholders.



                                       22

<PAGE>   33


         Pursuant to the terms of the engagement letter between BFC and CFA, BFC
has agreed to pay CFA a fee of $100,000 for its services as financial advisor,
including this fairness opinion. In addition, BFC has agreed to reimburse CFA
for its reasonable out-of-pocket expenses, including the fees and disbursements
of its counsel, and to indemnify CFA against certain liabilities.

                                   THE MERGER

         The following description of the material aspects of the Merger does
not purport to be complete and is qualified in its entirety by reference to the
Merger Agreement. USBN and BFC stockholders are being asked to approve the
Merger in accordance with the terms of the Merger Agreement, and are urged to
carefully read the Merger Agreement, which is attached at APPENDIX A.

BASIC TERMS OF THE MERGER

         The Merger Agreement provides for the merger of BFC with and into USBN.
The separate corporate existence of BFC will cease, and the Bank will become a
wholly-owned subsidiary of USBN. While USBN and BFC believe that they will
receive the requisite regulatory approvals for the Merger, there can be no
assurance that such approvals will be received or, if received, as to the timing
of such approvals or as to the ability to obtain such approvals on satisfactory
terms. See "-- Conditions to Consummation of the Merger; Regulatory Approvals."

         In the Merger, each BFC stockholder (except BFC stockholders who
exercise their dissenters' rights) will receive 4.7038 shares of USBN common
stock for each share of BFC common stock that they own, plus an additional
amount of shares, as applicable, determined by an "Adjustment Factor". The
Adjustment Factor essentially takes into account any net income generated by BFC
during the period from January 1, 1999 to the Merger closing date, and provides
for the issuance of additional shares to BFC stockholders to reflect such net
income.

         The additional shares of USBN common stock that will be issued pursuant
to the Adjustment Factor will be valued using the "Average Closing Price" of
USBN common stock. The Average Closing Price means a price equal to the average
of the daily sales prices (average high and low trading price on a particular
day) of USBN common stock on the ten consecutive trading days on which at least
2,000 shares of USBN common stock are traded, with the last such day being the
fifth day prior to the Merger effective date.

         Here is an example of how the Merger exchange ratio works:

         A stockholder owning 100 shares of BFC common stock will be entitled to
receive 470 shares of USBN common stock and cash payment for the remaining
fractional share of 38/100. (100 shares multiplied by 4.7038 equals 470.38
shares.) If the Average Closing Price of USBN common stock is $18, then the
stockholder will receive $6.84 for the fractional share. ($18 multiplied by 0.38
equals $6.84.) This example assumes that no net income has been generated by BFC
between January 1, 1999 and the effective Merger date and that, accordingly, the
Adjustment Factor has not been triggered.

         The following example shows how the Adjustment Factor would work, if
the Merger closes on January 31, 1999, and assuming (by way of example only)
that BFC's net income for the period between January 1, 1999 and January 31,
1999 was $175,000. Assuming, as in the example provided above, that the Average
Closing Price of USBN common stock is $18.00, then a total of 9,722 additional
shares of USBN common stock would be issued in the aggregate to BFC stockholders
in the Merger (175,000 / 18 = 9,722).



                                       23

<PAGE>   34


         Assuming that there are 364,281 shares of BFC common stock outstanding
on the Merger effective date and that no BFC stockholder exercises dissenters'
rights, each BFC stockholder would receive, in addition to the base exchange
ratio of 4.7038 USBN shares per one BFC share, a fractional share of 0.27 USBN
common stock (9,722 / 364,281 = 0.2668).

         Using the example in the preceding paragraph, a stockholder owning 100
shares of BFC common stock be entitled to receive 470 shares of USBN common
stock and $11.70 in lieu of a fractional share (100 shares of BFC common stock
entitle the holder to receive 470.38 shares of USBN common stock based on the
base exchange ratio of 4.7038, plus the additional 0.27 fractional share based
on the assumed Adjustment Factor, for a total of 470.65 shares of USBN common
stock. The fractional share of 0.65 is multiplied by the assumed Average Closing
Price of $18, resulting in $11.70). There can be no assurance as to the amount
of BFC net income, if any, that might be reflected in the Adjustment Factor.

         On December __, 1998, the most recent date for which it is practicable
to obtain information prior to the printing of this Prospectus/Joint Proxy
Statement, the closing price per share of USBN common stock, as reported on
Nasdaq, was $_________.

         Subject to the conditions set forth in the Merger Agreement, the
effective date of the Merger will occur as soon as possible after such
conditions have been satisfied or waived. Subject to those conditions, USBN and
BFC anticipate that the Merger will occur as early as January 31, 1999. Either
USBN or BFC may terminate the Merger Agreement if the Merger does not occur by
June 30, 1999.

CASH FOR FRACTIONAL SHARES

         USBN will not issue certificates for fractional shares of USBN common
stock. Each holder of BFC common stock who would otherwise be entitled to
receive a fractional share, will receive cash in lieu of such fractional share,
in an amount equal to the product of such fraction multiplied by the Average
Closing Price for USBN common stock, as described above under "--Basic Terms of
the Merger." Holders of BFC common stock will have no other rights with respect
to such fractional shares.

EXCHANGE OF BFC STOCK CERTIFICATES

         As promptly as practicable after the Merger effective date, USBN will
send or cause to be sent to each holder of record of BFC common stock
transmittal materials for use in exchanging all of such holder's certificates
representing BFC common stock for a certificate or certificates representing the
USBN common stock to which such holder is entitled and a check or checks for
such holder's fractional share interests, as appropriate. The transmittal
materials will contain information and instructions regarding the surrender and
exchange of such certificates.

         BFC STOCKHOLDERS SHOULD NOT SEND IN THEIR CERTIFICATES UNTIL THEY
RECEIVE THE LETTER OF TRANSMITTAL FORM AND INSTRUCTIONS.

         Upon surrender of all of the certificates for BFC common stock
registered in the name of a holder of such certificates (or indemnity
satisfactory to USBN and the exchange agent selected by USBN, if any of such
certificates are lost, stolen or destroyed), together with a properly completed
letter of transmittal, such exchange agent will mail to such holder a
certificate or certificates representing the number of shares of USBN common
stock to which such holder is entitled, together with all undelivered dividends
or distributions in respect of such shares and, where applicable, a check for
any fractional share interest (in each case, without interest).



                                       24

<PAGE>   35


         All shares of USBN common stock issued to the holders of BFC common
stock pursuant to the Merger will be deemed issued as of the Merger effective
date. USBN dividends having a record date after the Merger effective date will
include dividends on all shares of USBN common stock issued in the Merger, but
no dividend or other distribution payable to the holders of record of USBN
common stock at or as of any time after the Merger effective date will be
distributed to the holder of any BFC common stock certificates until such holder
physically surrenders all such certificates as described above. Promptly after
such surrender, all undelivered dividends and other distributions and, where
applicable, a check for any fractional share interest, will be delivered to such
holder, in each case, without interest. After the Merger effective date, the
stock transfer books of BFC will be closed, and there will be no transfers on
the transfer books of BFC of the shares of BFC common stock that were
outstanding immediately prior to the Merger effective date.

CONDITIONS TO CONSUMMATION OF THE MERGER; REGULATORY APPROVALS

         Consummation of the Merger is subject to various conditions. USBN and
BFC cannot provide any assurance as to whether these conditions will be
satisfied or waived by the appropriate party. Accordingly, there can be no
assurance that the Merger will be completed. If conditions to the Merger remain
unsatisfied after June 30, 1999, then either USBN's or BFC's boards of directors
may terminate the Merger Agreement.

         Under Washington law, approval of the Merger requires the affirmative
vote of two-thirds of the holders of all outstanding shares of USBN and BFC
common stock. In addition, the Federal Reserve Board must approve the Merger. An
application for prior approval by the Federal Reserve Board has been filed.
Although no assurance can be given, the parties expect to receive this approval
in due course.

         Certain conditions must be satisfied or events must occur before
parties will be obligated to complete the Merger. Each parties' obligations
under the Merger Agreement are conditioned on satisfaction by the other parties
of conditions applicable to them. Some of these conditions are as follows:

         -        The Merger Agreement's approval by the required vote of the
                  stockholders of USBN and BFC;

         -        The receipt of all necessary regulatory approvals, without any
                  condition or requirement that would, in USBN's opinion,
                  deprive USBN of the material benefits of the Merger;

         -        USBN's and BFC's receipt of an opinion from Graham & Dunn,
                  P.C. to the effect that, among other things, the Merger will
                  qualify as a tax-free reorganization under Section 368 of the
                  Internal Revenue Code; and

         -        USBN's receipt of a letter from Moss Adams, LLP, to the effect
                  that the Merger will qualify for "pooling of interests"
                  accounting treatment if it is consummated in accordance with
                  the Merger Agreement.

         Additionally, either USBN or BFC may terminate the Merger Agreement if
certain conditions applicable to the other party are not satisfied or waived.
Those conditions are discussed below under "--Amendment of Termination of the
Merger Agreement".

         Either USBN or BFC may waive any of the other party's conditions,
except those that are required by law (such as USBN and BFC stockholder approval
and the receipt of required regulatory approvals). Either USBN or BFC may also
grant extended time to the other party to complete an obligation or condition.



                                       25

<PAGE>   36


BFC STOCK OPTION AGREEMENT

         As an inducement to USBN to enter into the Merger Agreement, BFC has
granted an option (the "Option") to USBN, by agreement dated as of November 10,
1998 (the "Option Agreement") to purchase authorized but unissued shares of BFC
common stock, which, if issued, would constitute 19.9% of the issued BFC commons
stock, at $45.00 per share. USBN may only exercise the Option upon (i) the
occurrence of certain events set forth in the Option Agreement, and (ii) USBN's
obtaining of any regulatory approvals necessary for the acquisition of the BFC
common stock subject to the Option. Additionally, USBN must have performed all
of its obligations under the Merger Agreement. USBN may transfer the Option only
if an event occurs triggering USBN's right to exercise the Option. The effect of
the Option may be to make third-party offers or acquisition transactions less
attractive and therefore less likely. The Option Agreement is attached to this
Prospectus/Joint Proxy Statement as APPENDIX D.

AMENDMENT OR TERMINATION OF THE MERGER AGREEMENT: TERMINATION FEES

         The Merger Agreement may be amended or supplemented at any time by
written agreement of the parties, either before or after the USBN and BFC
special stockholders meetings. To the extent permitted by applicable law, the
parties may make any amendment or supplement without the further approval of
USBN's or BFC's stockholders. The Merger Agreement provides that USBN may at any
time change the method of effecting its acquisition of BFC and the Bank, but no
such change may change the amount of kind of consideration to be issued to
holders of BFC common stock, and no such change may adversely affect the tax
treatment to BFC stockholders as a result of receiving such consideration.

         The Merger Agreement contains several provisions entitling either USBN
or BFC to terminate the Merger Agreement under certain circumstances. The
following briefly describes some of those conditions:

         Lapse of Time. If the Merger has not closed by June 30, 1999, than at
any time after that date, the board of directors of either USBN or BFC may
terminate the Merger Agreement, as long as the party terminating has not caused
the delay in closing by breaching its obligations under the Merger Agreement.

         Mutual Consent. The parties may terminate the Merger Agreement at any
time before the Merger occurs, whether before or after USBN and BFC stockholder
approval, by mutual consent.

         Impracticability. The parties may terminate the Merger Agreement if the
party seeking termination, through its board of directors, has determined that
the Merger has become inadvisable or impracticable by reason of litigation by
the federal government or the government of Washington to restrain or invalidate
the Merger.

         Average Closing Price Below $12.50. BFC may terminate the Merger
Agreement if the Average Closing Price (see "--Basic Terms of the Merger") is
less than $12.50, and USBN, in its sole discretion, does not elect to increase
the Merger exchange ratio so that the Average Closing Price multiplied by such
increased exchange ratio equals the Merger exchange ratio multiplied by $12.50.
In determining whether to terminate the Merger Agreement in these circumstances,
the BFC board of directors will take into account, consistent with its fiduciary
duties, all relevant facts and circumstances existing at the time, including
without limitation, the market for financial stocks in general, the relative
value of USBN common stock in the market, and the advice of its financial
advisors and legal counsel. By approving the Merger Agreement, BFC stockholders
would be permitting the BFC board of directors to determine, in the exercise of
its fiduciary duties, to proceed with the Merger even though the Average Closing
Price of USBN common stock is under $12.50. This termination right of BFC, as
noted above, is subject to USBN's right to avoid termination by increasing the
number of USBN shares that BFC stockholders will receive.



                                       26

<PAGE>   37


         USBN's Conditions Not Met. BFC may terminate the Merger Agreement if,
by June 30, 1999, any of USBN's conditions to closing are not met. Among such
conditions are (i) there must have been no material adverse change in the
financial position or results of operations of USBN, and (ii) USBN must have
complied with all terms, covenants and conditions of the Merger Agreement.

         BFC's Conditions Not Met. USBN may terminate the Merger Agreement if,
by June 30, 1999, any of BFC's conditions are not met. Among such conditions
are: (i) BFC's Capital (as defined in the Merger Agreement) must be at least $12
million on the Merger effective date; (ii) the Bank's allowance for possible
loan and lease losses must be not less than 1% of the Bank's total outstanding
loans, based on USBN's reasonable analysis; (iii) and there must have been no
material change in the financial position or results of operations of BFC or the
Bank; and (iv) BFC must have complied with all of the terms covenants and
conditions of the Merger Agreement.

         USBN Cash Payments. USBN may terminate the Merger Agreement if the
number of shares of BFC common stock for which cash is to be paid because the
holders have exercised dissenters' rights, together with the number of
fractional shares for which cash will be paid, exceeds 10% of the number of
outstanding shares of BFC common stock.

         Termination Fees. If either USBN or BFC terminates the Merger Agreement
under certain circumstances, or if the Merger Agreement terminates because
either party did not use its best efforts to consummate the Merger, then the
party that terminated the Merger Agreement (other than for reasons allowed by
the Merger Agreement) or did not use its best efforts to consummate the Merger,
must pay the other party a termination fee of $500,000.

         Allocation of Costs Upon Termination. If the Merger Agreement is
terminated, USBN and BFC will each pay their own out-of-pocket expenses incurred
in connection with the transaction, and, except for any applicable termination
fees, will have no other liability to the other party.

CONDUCT OF BUSINESS PENDING THE MERGER

         BFC and the Bank have agreed in the Merger Agreement not to take
certain actions without the prior approval of USBN relating to their operations
pending consummation of the Merger. Among other things, BFC and the Bank may
not:

         -        issue or sell any common stock;

         -        pay any dividends;

         -        incur any indebtedness for borrowed money or becoming liable
                  for the obligations of any other entity other than in the
                  ordinary course of business;

         -        change their lending, investment, liability management or
                  other material banking policies in any respect;

         -        impose any lien on any share of stock held by BFC;

         -        enter into or amend any employment agreements or any employee
                  benefit plans or grant any increases, other than in the
                  ordinary course of business;

         -        dispose of any material portion of their assets or acquire any
                  material portion of the business or property of any other
                  entity;



                                       27

<PAGE>   38


         -        amend their articles of incorporation or bylaws;

         -        settle any claims involving any liability for material money
                  damages;

         -        enter into, terminate or change any material agreements,
                  except for those agreements that may be terminated by BFC or
                  the Bank without penalty upon not more than 60 days' prior
                  written notice; and

         -        extend credit other than in accordance with existing lending
                  policies, with specific exceptions granted to BFC and the
                  Bank.

         Additionally, BFC is required, among other things, to operate its
businesses in the usual, regular and ordinary course and to use its best efforts
to preserve its business relationships and to retain key employees.

DIRECTORS AND EXECUTIVE OFFICERS AFTER THE MERGER

         Upon consummation of the Merger, the USBN board of directors will
consist of USBN's current directors plus three current BFC directors. Mr. Wes
Colley, Chairman of BFC's board, has been designated as one of the three persons
who will serve on the USBN board; the other two persons have not yet been
designated. The Bank's board will consist of the Bank's current directors, plus
two additional directors to be designated by USBN. The executive officers of
USBN in office immediately before the Merger effective date will remain
unchanged following the Merger. The executive officers of the Bank will remain
unchanged immediately following the Merger.

         As a condition to the execution of the Merger Agreement, each member of
the BFC and/or Bank board of directors has executed a Director NonCompetition
Agreement with USBN. The Director NonCompetition Agreement prohibits such
directors from competing with USBN or any of its subsidiaries for two years
after the Merger effective date within Walla Walla County, Washington.

EMPLOYEE BENEFIT PLANS

         The Merger Agreement confirms USBN's intention to allow the employees
of the Bank who continue as employees after the Merger to participate in certain
USBN employee benefit plans, on substantially the same terms as employees of
USBN and its other subsidiaries. For the purposes of determining eligibility to
participate in such plans, and the vesting of benefits under such plans (but not
the accrual of benefits under such plans) USBN will give effect to years of
service with the Bank as though such service were with USBN. On the Merger
effective date, all outstanding and unexercised options to purchase BFC common
stock will be converted into options to purchase USBN common stock, adjusted as
to both number of shares and price using the Merger exchange ratio.

INTERESTS OF CERTAIN PERSONS IN THE MERGER

         The directors and executive officers of BFC, together with their
affiliates, beneficially owned a total of 111,857 shares of BFC common stock
(representing 28.5 % of all outstanding shares of BFC common stock) as of the
Merger record date. The directors and executive officers will receive the same
consideration in the Merger for their shares, including any shares which they
may acquire prior to the Merger effective date pursuant to the exercise of stock
options, as the other stockholders of BFC. Wes Colley, the President and
Chairman of the Bank, and BFC's board of directors have certain interests in the
Merger as described below that are in addition to their interest as stockholders
of BFC generally. BFC's board of directors was aware of these interests and
considered them, among other matters, in approving the Merger Agreement and the
transactions contemplated by the Merger Agreement.



                                       28

<PAGE>   39


         Directors' and Officers' Liability. The Merger Agreement provides that
for the four-year period following the Merger effective date, USBN will
indemnify the directors, officers and employees of BFC and the Bank against
certain liabilities to the extent that such persons were entitled to
indemnification under federal or Washington law and the articles of
incorporation and bylaws of BFC or the Bank. The indemnification provisions
applicable to such persons prior to the Merger effective date are summarized at
"COMPARISON OF CERTAIN RIGHTS OF HOLDERS OF USBN AND BFC COMMON STOCK --
Indemnification and Limitation of Liability."

         Employment Agreement. USBN has entered into an employment agreement
with Wes Colley, President and Chairman of the Bank. Mr. Colley's agreement is
for a term of 36 months commencing on the Merger effective date. Mr. Colley's
initial base salary under the agreement will be $108,600. The agreement further
provides that Mr. Colley will receive all benefits that are generally provided
to similarly situated full-time employees of USBN. Mr. Colley will also receive
certain fringe benefits, including, the right to participate in group life
insurance, disability, health and accident insurance plans, profit sharing and
pension plans and other employee fringe benefit plans that the Bank or USBN may
have in effect from time to time for similarly situated employees. If Mr. Colley
is terminated without cause or Mr. Colley terminates his employment for a
legitimate reason as defined in his agreement before the end of the term of the
agreement, Mr. Colley is entitled to receive his base salary for the remaining
term of the agreement. The employment agreement also provides for a restriction
on Mr. Colley's ability to compete with USBN or the Bank following his
termination from employment (voluntary or otherwise).

         Director and Executive Officer Non-Competition Agreements. Each
director and executive officer of BFC and the Bank has signed an agreement which
restricts such person's ability to compete with USBN or any of its subsidiaries
or affiliates within Walla Walla County, Washington for a period of two years
after the effective date of the Merger.

         Positions on the USBN Board. The Merger Agreement provides that USBN
will appoint three current members of the BFC board of directors to the USBN
board of directors following the effective date of the Merger. Mr. Colley has
been designated as one of the persons who will serve on the USBN board; the
other two persons have not yet been designated.

FEDERAL INCOME TAX TREATMENT OF THE MERGER

         The following is a discussion of the material federal income tax
consequences of the Merger that are generally applicable to BFC stockholders.
This discussion is based on currently existing provisions of the Internal
Revenue Code of 1986, as amended, existing Treasury regulations thereunder
(including final, temporary or proposed), and current administrative rulings and
court decisions, all of which are subject to change. Any such change, which may
or may not be retroactive, could alter the tax consequences described herein.
The following discussion is intended only as a summary of the material federal
income tax consequences of the Merger and does not purport to be a complete
analysis or listing of all of the potential tax effects relevant to a decision
on whether to vote in favor of approval of the Merger.

         The Merger is expected to qualify as a reorganization under Section 368
of the Internal Revenue Code. As parties to a reorganization, neither USBN nor
BFC will recognize gain or loss as a result of the Merger. Except for cash
received in lieu of a fractional share interest in USBN common stock, holders of
shares of BFC common stock will recognize no gain or loss on the receipt of USBN
common stock.

         Consummation of the Merger is conditioned upon the receipt by USBN and
BFC of an opinion of Graham & Dunn, P.C., special counsel to USBN, to the effect
that if the Merger is consummated within the meaning of Section 368 of the
Internal Revenue Code, no gain or loss will be recognized by BFC stockholders
who exchange all 



                                       29

<PAGE>   40


of their BFC common stock solely for shares of USBN common stock (except for
cash received in lieu of fractional shares).

         The opinion of counsel, which will be delivered on the closing date of
the Merger, is filed as an exhibit to the Registration Statement, and the
foregoing is only a summary of the tax consequences of the Merger as described
in the opinion. An opinion of counsel only represents counsel's best legal
judgment, and has no binding effect or official status of any kind, and no
assurance can be given that contrary positions may not be taken by the Internal
Revenue Service or a court considering these issues. Neither USBN nor BFC has
requested or will request a ruling from the IRS with regard to the federal
income tax consequences of the Merger.

         The tax basis of the USBN common stock received in the Merger by BFC
stockholders will be the same as the tax basis of the BFC common stock
surrendered in the exchange therefor, reduced by any basis allocable to a
fractional share interest in BFC common stock for which cash is received. The
holding period for the shares of USBN common stock received in the Merger will
include the holding period of BFC common stock exchanged therefor, provided that
BFC shares were held as capital assets at the time of the Merger.

         Gain or loss will be recognized by BFC stockholders who receive cash in
lieu of fractional shares of USBN common stock, or who exercise dissenters'
rights and receive cash for their BFC shares. The amount of such gain or loss
will be the difference between the cash received and the basis of the shares or
fractional share interests surrendered in the exchange. Generally, such gain or
loss will be a capital gain or loss provided that the shares of BFC surrendered
were capital assets at the time of surrender, and will be long-term capital gain
or loss if such shares of BFC common stock have been held for more than one
year.

         THE FOREGOING IS A GENERAL SUMMARY OF THE MATERIAL FEDERAL INCOME TAX
CONSEQUENCES OF THE MERGER TO BFC STOCKHOLDERS, WITHOUT REGARD TO THE PARTICULAR
FACTS AND CIRCUMSTANCES OF EACH STOCKHOLDER'S TAX SITUATION AND STATUS. IN
ADDITION, THERE MAY BE RELEVANT STATE, LOCAL OR OTHER TAX CONSEQUENCES, NONE OF
WHICH ARE DESCRIBED ABOVE. BECAUSE CERTAIN TAX CONSEQUENCES OF THE MERGER MAY
VARY DEPENDING UPON THE PARTICULAR CIRCUMSTANCES OF EACH STOCKHOLDER, EACH BFC
STOCKHOLDER SHOULD CONSULT HIS OR HER OWN TAX ADVISOR REGARDING SUCH
STOCKHOLDER'S SPECIFIC TAX SITUATION AND STATUS, INCLUDING THE SPECIFIED
APPLICATION AND EFFECT OF STATE, LOCAL AND FOREIGN LAWS TO SUCH STOCKHOLDER AND
THE POSSIBLE EFFECT OF CHANGE IN FEDERAL AND OTHER TAX LAWS.

ACCOUNTING TREATMENT OF MERGER

         It is anticipated that the Merger will be accounted for as a "pooling
of interests" for accounting purposes. Under this method of accounting, assets
and liabilities of USBN and BFC are carried forward at their previously recorded
amounts, and operating results of USBN and BFC will represent the combined
results for periods before and after the Merger. No recognition of goodwill
arising from the Merger is required of any party to the Merger.

         USBN's receipt of a letter from Moss Adams, LLP, to the effect that
they concur with management's understanding that the Merger will qualify as a
"pooling of interests" if consummated in accordance with the Merger Agreement,
is a condition to the closing the Merger.

DISSENTERS' RIGHTS OF APPRAISAL

         In accordance with Chapter 23B.13 of the Revised Code of Washington
("RCW"), BFC stockholders have the right to dissent from the Merger and to
receive payment in cash for the "fair value" of their BFC common stock.



                                       30

<PAGE>   41


         If BFC stockholders perfect dissenters' rights with respect to more
than 10% of the outstanding shares of BFC common stock, USBN may elect not to
consummate the Merger. BFC stockholders electing to exercise dissenters' rights
must comply with the provisions of RCW Chapter 23B.13 in order to perfect their
rights. BFC and USBN will require strict compliance with the statutory
procedures. The following is intended as a brief summary of the material
provisions of the Washington statutory procedures required to be followed by a
BFC stockholder in order to dissent from the Merger and perfect the
stockholder's dissenters' rights. THIS SUMMARY, HOWEVER, IS NOT A COMPLETE
STATEMENT OF ALL APPLICABLE REQUIREMENTS AND IS QUALIFIED IN ITS ENTIRETY BY
REFERENCE TO RCW CHAPTER 23B.13, THE FULL TEXT OF WHICH IS SET FORTH IN APPENDIX
E.

         A stockholder who wishes to assert dissenters' rights must (a) deliver
to BFC before the vote is taken by BFC stockholders written notice of the
stockholder's intent to demand payment for the stockholder's shares if the
Merger is effected, and (b) not vote such shares in favor of the Merger. A
stockholder wishing to deliver such notice should hand deliver or mail such
notice to BFC at the following address within the requisite time period:

                         Bancwest Financial Corporation
                                 P. O. Box 1597
                          Walla Walla, Washington 99362
                           Attn: Wes Colley, President

         A stockholder who wishes to exercise dissenters' rights generally must
dissent with respect to all the shares the stockholder owns or over which the
stockholder has power to direct the vote. However, if a record stockholder is a
nominee for several beneficial stockholders some of whom wish to dissent and
some of whom do not, then the record holder may dissent with respect to all the
shares beneficially owned by any one person by notifying BFC in writing of the
name and address of each person on whose behalf the record stockholder asserts
dissenters' rights. A beneficial stockholder may assert dissenters' rights
directly by submitting to BFC the record stockholder's written consent and by
dissenting with respect to all the shares of which such stockholder is the
beneficial stockholder or over which such stockholder has power to direct the
vote.

         A STOCKHOLDER WHO DOES NOT DELIVER TO BFC PRIOR TO THE VOTE BEING TAKEN
BY BFC STOCKHOLDERS A WRITTEN NOTICE OF THE STOCKHOLDER'S INTENT TO DEMAND
PAYMENT FOR THE "FAIR VALUE" OF THE SHARES WILL LOSE THE RIGHT TO EXERCISE
DISSENTERS' RIGHTS. IN ADDITION, ANY STOCKHOLDER ELECTING TO EXERCISE
DISSENTERS' RIGHTS MUST EITHER VOTE AGAINST THE MERGER OR ABSTAIN FROM VOTING.

         If the Merger is effected, USBN as the surviving corporation shall,
within ten days after the effective date of the Merger, deliver a written notice
to all stockholders who properly perfected their dissenters' rights in
accordance with RCW Chapter 23B.13. Such notice will, among other things: (a)
state where the payment demand must be sent and where and when certificates for
certificated shares must be deposited; (b) inform holders of uncertificated
shares to what extent transfer of the shares will be restricted after the
payment demand is received; (c) supply a form for demanding payment; and (d) set
a date by which USBN must receive the payment demand, which date will be between
30 and 60 days after notice is delivered.

         A stockholder wishing to exercise dissenters' rights must timely file
the payment demand and deliver share certificates as required in the notice.
Failure to do so will cause such person to lose his or her dissenters' rights.

         Within 30 days after the Merger occurs or receipt of the payment
demand, whichever is later, USBN shall pay each dissenter with properly
perfected dissenters' rights USBN's estimate of the "fair value" of the
stockholder's interest, plus accrued interest from the Effective Date of the
Merger. With respect to a dissenter who did not beneficially own BFC shares
prior to the public announcement of the Merger, USBN is required to make the
payment only after the dissenter has agreed to accept the payment in full
satisfaction of the dissenter's 



                                       31

<PAGE>   42


demands. "Fair value" means the value of the shares immediately before the
effective date of the Merger, excluding any appreciation or depreciation in
anticipation of the Merger. The rate of interest is generally required to be the
rate at which USBN can borrow money from other banks.

         A dissenter who is dissatisfied with USBN's estimate of the fair value
or believes that interest due is incorrectly calculated may notify USBN of the
dissenter's estimate of the fair value and amount of interest due. If USBN does
not accept the dissenter's estimate and the parties do not otherwise settle on a
fair value then USBN must within 60 days petition a court to determine the fair
value.

         In view of the complexity of RCW Chapter 23B.13 and the requirement
that stockholders must strictly comply with the provisions of RCW Chapter
23B.13, stockholders of BFC who may wish to dissent from the Merger and pursue
appraisal rights should consult their legal advisors.

RESALE OF USBN COMMON STOCK

         The USBN common stock to be issued in the Merger will be transferable
free of restrictions under the 1933 Act, except for shares received by persons,
including directors and executive officers of BFC, who may be deemed to be
"affiliates" of BFC, as that term is used in (i) paragraphs (c) and (d) of Rule
145 under the 1933 Act and/or (ii) Accounting Series Releases 130 and 135, as
amended, of the SEC. Affiliates may not sell their shares of USBN common stock
acquired in the Merger, except (a) pursuant to an effective registration
statement under the 1933 Act covering those shares, (b) in compliance with Rule
145, or (c) in accordance with an opinion of counsel reasonably satisfactory to
USBN, under other applicable exemptions from the registration requirements of
the 1933 Act. SEC guidelines further indicate that the pooling of interests
method of accounting will generally not be challenged on the basis of sales by
affiliates of the acquiring or acquired company if such affiliates do not
dispose of any of the shares of the acquiring or acquired company they owned
before the consummation of a merger or shares of the acquiring corporation they
receive in connection with the merger during the period beginning 30 days before
the Merger effective date and ending when financial results covering at least 30
days of post-merger operations of the combined organization have been published.
USBN will obtain customary agreements with all BFC directors, officers, and
affiliates of BFC and USBN, under which such persons have represented that they
will not dispose of their shares of USBN common stock received in the Merger or
the shares of BFC common stock or USBN common stock held by them before the
Merger, except (i) in compliance with the 1933 Act and the rules and regulations
promulgated thereunder, and (ii) in a manner that would not adversely affect the
ability of USBN to treat the Merger as a pooling of interests for financial
reporting purposes. This Prospectus/Joint Proxy Statement does not cover any
resales of the USBN common stock received by affiliates of BFC.

NO SOLICITATION

         BFC has agreed in the Merger Agreement that, except as required by law,
neither it, the Bank, nor any of its officers or directors will (i) solicit,
initiate or encourage inquiries or proposals for the acquisition of the shares
or assets of BFC (an "Acquisition Proposal"), (ii) enter into discussions
concerning any such Acquisition Proposal, or (iii) furnish any nonpublic
information relating to an Acquisition Proposal.

EXPENSES

         The Merger Agreement provides that USBN and BFC will each pay their own
expenses in connection with the Merger Agreement and the transactions
contemplated by the Merger Agreement.



                                       32

<PAGE>   43


                              DIRECTOR CONFIRMATION

         Consistent with the articles of incorporation of the Bank prior to
BFC's formation as a bank holding company, the stockholders of BFC have
historically elected the BFC board of directors to staggered terms. This means
that the board of directors has been divided into three classes, with each class
being elected for a term of three years (a "Classified Board"). Thus, one-third
of the entire board of directors are elected on a rotating basis each year.
BFC's Articles of Incorporation do not, however, specifically provide for a
Classified Board.

         In order to remedy this discrepancy and to eliminate any possible
ambiguity regarding the composition of the BFC board of directors, BFC's
stockholders are being asked to confirm the present composition of the BFC board
of directors, and to adopt the acts of the Classified Board, previously taken on
behalf of and in the name of BFC, as the fully authorized acts of the BFC board
of directors. These acts include, but are not limited to, the annual election of
Bank directors, the approval of stock option plans and the related grants of
options, and the approval of the Merger Agreement.

         The BFC Board of Directors consists of six persons: Messrs. Wes Colley,
Harold Cochran, David Frame, Mark Graves, Allen Ketelson and Norman McKibben.
Each of such persons has previously been elected by BFC's stockholders to serve
as a member of the BFC board of directors, at a BFC annual stockholders meeting.
By approving the proposal to confirm the composition of the BFC board of
directors, BFC stockholders will resolve the possible ambiguity resulting from
the fact that the directors have been annually elected in classes of two instead
of having been annually elected as an entire slate of six.

         THE BFC BOARD OF DIRECTORS RECOMMENDS THAT THE STOCKHOLDERS OF BFC VOTE
FOR THE APPROVAL OF THE DIRECTOR CONFIRMATION.



                                       33


<PAGE>   44



           PRO FORMA CONDENSED COMBINED UNAUDITED FINANCIAL STATEMENTS

         The following pro forma condensed combined unaudited financial
statements give effect to the Merger on a pooling of interests basis. The
unaudited pro forma condensed combined statements of financial condition are
presented on the basis that as of the beginning of the first period presented
the Merger was consummated on September 30, 1998. The unaudited pro forma
condensed combined statements of income are presented on the basis that the
Merger was consummated as of the beginning of the first period presented.

         Effective July 20, 1998, USBN acquired Grant National Bank ("GNB"),
located in Ephrata, Washington. The pooling of interests method of accounting
was used for the transaction. Accordingly, all prior period USBN financial
information has been restated to reflect the acquisition of GNB. The pro forma
condensed combined unaudited USBN financial statements included in this document
include the accounts of GNB. Effective October 1, 1997, USBN acquired the Bank
of Pullman ("BOP"), located in Pullman, Washington. The purchase method of
accounting was used for the transaction. Accordingly, prior period financial
statements for USBN have not been restated to reflect the accounts of BOP before
October 1, 1997. The pro forma condensed combined unaudited financial statements
included in this document include the accounts of BOP since October 1, 1997.

         These pro forma condensed combined unaudited financial statements
should be read in conjunction with the historical financial statements and the
related notes thereto for USBN and BFC included or incorporated into this
Prospectus/Joint Proxy Statement by reference. See "WHERE YOU CAN FIND MORE
INFORMATION," "INFORMATION INCORPORATED BY REFERENCE" and the USBN Form 10-K for
the year ended December 31, 1997, the USBN Form 10-Q for the quarter ended
September 30, 1998 and the USBN Proxy Statement for its 1998 Annual Meeting of
Stockholders.

         The pro forma condensed unaudited statements of income are not
necessarily indicative of operating results, which would have been achieved had
the Merger been consummated as of the beginning of the first period presented
and should not be construed as representative of future results.



                                       34

<PAGE>   45



UNITED SECURITY BANCORPORATION AND BANCWEST FINANCIAL CORPORATION PRO FORMA
CONDENSED COMBINED UNAUDITED STATEMENT OF FINANCIAL CONDITION AT SEPTEMBER 30,
1998

<TABLE>
<CAPTION>
                                                                                          PRO FORMA
($ in thousands, except per share) Assets                    USBN             BFC          COMBINED
                                                          ---------       ---------       ----------
<S>                                                       <C>             <C>             <C>      
Cash and due from banks                                   $  16,541       $   2,288       $  18,829
Overnight interest bearing deposits with other banks         14,860                          14,860
Federal funds sold                                           15,410             725          16,135
Securities                                                   50,056          26,624          76,680
Loans, net of allowance for loan losses                     282,239          70,345         352,584
Accrued interest receivable                                   3,860           1,599           5,459
Premises and equipment, net                                  10,063           2,184          12,247
Foreclosed assets                                               794              80             874
Life insurance and salary continuation assets                 3,317              83           3,400
Intangible assets                                             6,617                           6,617
Other assets                                                    910             156           1,066
                                                          ---------       ---------       ---------
     Total assets                                         $ 404,667       $ 104,084       $ 508,751
                                                          =========       =========       =========

                       Liabilities
Noninterest bearing - demand deposits                     $  60,068       $  17,107       $  77,175
Interest bearing:
  NOW and savings accounts                                  166,602          28,853         195,455
  Time, $100,000 and over                                    36,576          21,024          57,600
  Other time                                                 91,583          23,188         114,771
                                                          ---------       ---------       ---------
     Total deposits                                         354,829          90,172         445,001

Federal funds purchased                                                         677             677
Notes payable                                                 4,456                           4,456
Capital lease obligations                                       718                             718
Accrued interest payable                                      1,146             512           1,658
Other liabilities                                             2,669           1,002           3,671
     Total liabilities                                      363,818          92,363         456,181

                  Stockholders' Equity
Common stock                                                 30,479           4,163          34,642
Retained earnings                                            10,352           7,340          17,692
Accumulated other comprehensive income, net of tax              113             218             331
Guaranteed bank loan to ESOP                                    (95)                            (95)
                                                          ---------       ---------       ---------
     Total stockholders' equity                              40,849          11,721          52,570
                                                          ---------       ---------       ---------
     Total liabilities and stockholders' equity           $ 404,667       $ 104,084       $ 508,751
                                                          =========       =========       =========
</TABLE>


See notes to pro forma condensed combined unaudited financial statements.



                                       35

<PAGE>   46



UNITED SECURITY BANCORPORATION AND BANCWEST FINANCIAL CORPORATION PRO FORMA
CONDENSED COMBINED UNAUDITED INCOME STATEMENT FOR THE NINE MONTHS ENDED
SEPTEMBER 30, 1998

<TABLE>
<CAPTION>
($ in thousands, except per share)                                                             PRO FORMA
Interest Income:                                                 USBN            BFC           COMBINED
                                                              ----------      ----------      ----------
<S>                                                           <C>             <C>             <C>       
Interest and fees on loans and leases                         $   22,174      $    5,536      $   27,710
Interest on securities                                             2,975           1,198           4,173
Other interest income                                                510              11             521
                                                              ----------      ----------      ----------
     Total interest income                                        25,659           6,745          32,404
                                                              ----------      ----------      ----------

Interest expense:
Interest on deposits                                               9,693           2,451          12,144
Interest on borrowings                                               613             203             816
                                                              ----------      ----------      ----------
     Total interest expense                                       10,306           2,654          12,960
                                                              ----------      ----------      ----------

     Net interest income                                          15,353           4,091          19,444
Provision for loan losses                                            324             100             424
                                                              ----------      ----------      ----------
     Net interest income after provision for loan losses          15,029           3,991          19,020
                                                              ----------      ----------      ----------

Noninterest income:
Fees and service charges                                           1,282             455           1,737
Insurance commissions                                                817                             817
Securities gains/(losses)                                             91               7              98
Other                                                              1,113             277           1,390
                                                              ----------      ----------      ----------
     Total noninterest income                                      3,303             739           4,042
                                                              ----------      ----------      ----------

Noninterest expense:
Salaries and employee benefits                                     6,990           1,549           8,539
Occupancy expense, net                                               896             302           1,198
Equipment expense                                                    940                             940
Other operating expense                                            3,255             530           3,785
                                                              ----------      ----------      ----------
     Total noninterest expense                                    12,081           2,381          14,462
                                                              ----------      ----------      ----------

     Income before tax                                             6,251           2,349           8,600
Income tax expense                                                 2,015             690           2,705
                                                              ----------      ----------      ----------
     Net income                                               $    4,236      $    1,659      $    5,895
                                                              ==========      ==========      ==========
Basic earnings per share                                      $     0.94      $     0.90      $     0.92
Diluted earnings per share                                    $     0.92      $     0.90      $     0.91
Basic weighted average shares outstanding                      4,524,262       1,850,000       6,374,262
Diluted weighted average shares outstanding                    4,597,325       1,850,000       6,447,325
</TABLE>


See notes to pro forma condensed combined unaudited financial statements.



                                       36


<PAGE>   47





UNITED SECURITY BANCORPORATION AND BANCWEST FINANCIAL CORPORATION PRO FORMA
CONDENSED COMBINED UNAUDITED INCOME STATEMENT FOR THE YEAR ENDED DECEMBER 31,
1997

<TABLE>
<CAPTION>
($ in thousands, except per share)                                                                                 PRO FORMA
Interest Income:                                                 USBN             BOP(1)             BFC            COMBINED
                                                              -----------       -----------      -----------      -----------
<S>                                                           <C>               <C>              <C>              <C>        
Interest and fees on loans and leases                         $    23,571       $     2,678      $     6,682      $    32,931
Interest on securities                                              2,403               868            1,720            4,991
Other interest income                                               1,274                58                8            1,340
                                                              -----------       -----------      -----------      -----------
     Total interest income                                         27,248             3,604            8,410           39,262
                                                              -----------       -----------      -----------      -----------

Interest expense:
Interest on deposits                                               10,251             1,284            3,054           14,589
Interest on borrowings                                                432                16              224              672
                                                              -----------       -----------      -----------      -----------
     Total interest expense                                        10,683             1,300            3,278           15,261
                                                              -----------       -----------      -----------      -----------

     Net interest income                                           16,565             2,304            5,132           24,001
Provision for loan losses                                             752                 7              303            1,062
                                                              -----------       -----------      -----------      -----------
     Net interest income after provision for loan losses           15,813             2,297            4,829           22,939
                                                              -----------       -----------      -----------      -----------

Noninterest income:
Fees and service charges                                            1,525               191              598            2,314
Insurance commissions                                               1,125                 2                             1,127
Insurance proceeds                                                    796                                                 796
Securities gains/(losses)                                             (21)                3                5              (13)
Other                                                                 532                50              272              854
                                                              -----------       -----------      -----------      -----------
     Total noninterest income                                       3,957               246              875            5,078
                                                              -----------       -----------      -----------      -----------

Noninterest expense:
Salaries and employee benefits                                      7,145               989            1,918           10,052
Occupancy expense, net                                                831               125              338            1,294
Equipment expense                                                     899               196                             1,095
Other operating expense                                             3,139               426              635            4,200
                                                              -----------       -----------      -----------      -----------
     Total noninterest expense                                     12,014             1,736            2,891           16,641
                                                              -----------       -----------      -----------      -----------

     Income before taxes                                            7,756               807            2,813           11,376
Income tax expense                                                  2,464               186              882            3,532
                                                              -----------       -----------      -----------      -----------
     Net income                                               $     5,292       $       621      $     1,931      $     7,844
                                                              ===========       ===========      ===========      ===========
Basic earnings per share                                      $      1.17                        $      1.04      $      1.23
Diluted earnings per share                                    $      1.16                        $      1.04      $      1.22
Basic weighted average shares outstanding                       4,520,068                          1,850,000        6,370,068
Diluted weighted average shares outstanding                     4,563,748                          1,850,000        6,413,748
</TABLE>


(1) USBN acquired Bank of Pullman (BOP) effective October 1, 1997. The purchase
method of accounting was used for the transaction. This column is the results
prior to acquisition from January 1, 1997 through September 30, 1997. The
results from October 1, 1997 through December 31, 1997 are included with USBN.

See notes to pro forma condensed combined unaudited financial statements.



                                       37

<PAGE>   48


UNITED SECURITY BANCORPORATION AND BANCWEST FINANCIAL CORPORATION PRO FORMA
CONDENSED COMBINED UNAUDITED INCOME STATEMENT FOR THE NINE MONTHS ENDED
SEPTEMBER 30, 1997


<TABLE>
<CAPTION>
                                                                                     USBN &
($ in thousands, except per share)                                                     BOP                             PRO FORMA
Interest Income:                                    USBN             BOP(1)         COMBINED             BFC            COMBINED
                                                -----------       -----------      -----------       -----------      -----------
<S>                                             <C>               <C>              <C>               <C>              <C>        
Interest and fees on loans and leases           $    16,667       $     2,678      $    19,345       $     4,995      $    24,340
Interest on securities                                1,338               868            2,206             1,269            3,475
Other interest income                                   914                58              972                 7              979
                                                -----------       -----------      -----------       -----------      -----------
     Total interest income                           18,919             3,604           22,523             6,271           28,794
                                                -----------       -----------      -----------       -----------      -----------

Interest expense:
Interest on deposits                                  7,039             1,284            8,323             2,257           10,580
Interest on borrowings                                  231                16              247               190              437
                                                -----------       -----------      -----------       -----------      -----------
     Total interest expense                           7,270             1,300            8,570             2,447           11,017
                                                -----------       -----------      -----------       -----------      -----------

     Net interest income                             11,649             2,304           13,953             3,824           17,777
Provision for loan losses                               548                 7              555                57              612
                                                -----------       -----------      -----------       -----------      -----------
     Net interest income after
        provision for loan losses                    11,101             2,297           13,398             3,767           17,165
                                                -----------       -----------      -----------       -----------      -----------

Noninterest income:
Fees and service charges                              1,088               191            1,279               433            1,712
Insurance commissions                                   893                 2              895                                895
Insurance proceeds                                      796                                796                                796
Securities gains/(losses)                               (25)                3              (22)                3              (19)
Other                                                   420                50              470               164              634
                                                -----------       -----------      -----------       -----------      -----------
     Total noninterest income                         3,172               246            3,418               600            4,018
                                                -----------       -----------      -----------       -----------      -----------

Noninterest expense:
Salaries and employee benefits                        4,946               989            5,935             1,417            7,352
Occupancy expense, net                                  556               125              681               228              909
Equipment expense                                       593               196              789                                789
Other operating expense                               2,216               426            2,642               414            3,056
                                                -----------       -----------      -----------       -----------      -----------
     Total noninterest expense                        8,311             1,736           10,047             2,059           12,106
                                                -----------       -----------      -----------       -----------      -----------

     Income before taxes                              5,962               807            6,769             2,308            9,077
Income tax expense                                    1,966               186            2,152               648            2,800
                                                -----------       -----------      -----------       -----------      -----------
     Net income                                 $     3,996       $       621      $     4,617       $     1,660      $     6,277
                                                ===========       ===========      ===========       ===========      ===========
Basic earnings per share                        $      0.88                        $      1.02       $      0.90      $      0.99
Diluted earnings per share                      $      0.88                        $      1.01       $      0.90      $      0.98
Basic weighted average shares outstanding         4,519,794                          4,519,794        1,850,000         6,369,794
Diluted weighted average shares outstanding       4,557,133                          4,557,133        1,850,000         6,407,133
</TABLE>


(1) USBN acquired Bank of Pullman (BOP) effective October 1, 1997. The purchase
method of accounting was used for the transaction. This column is the results
prior to acquisition from January 1, 1997 through September 30, 1997.

See notes to pro forma condensed combined unaudited financial statements.



                                       38


<PAGE>   49





UNITED SECURITY BANCORPORATION AND BANCWEST FINANCIAL CORPORATION PRO FORMA
CONDENSED COMBINED UNAUDITED INCOME STATEMENT FOR THE YEAR ENDED DECEMBER 31,
1996

<TABLE>
<CAPTION>

($ in thousands, except per share)                                                                                PRO FORMA
Interest Income:                                                 USBN             BOP(1)             BFC           COMBINED
                                                              -----------      -----------       -----------      -----------
<S>                                                           <C>              <C>               <C>              <C>        
Interest and fees on loans and leases                         $    20,545      $     3,415       $     6,230      $    30,190
Interest on securities                                              1,472            1,155             1,504            4,131
Other interest income                                                 888               93                23            1,004
                                                              -----------      -----------       -----------      -----------
     Total interest income                                         22,905            4,663             7,757           35,325
                                                              -----------      -----------       -----------      -----------

Interest expense:
Interest on deposits                                                8,494            1,653             2,789           12,936
Interest on borrowings                                                297               33               135              465
     Total interest expense                                         8,791            1,686             2,924           13,401

     Net interest income                                           14,114            2,977             4,833           21,924
Provision for loan losses                                           1,021                                               1,021
                                                              -----------      -----------       -----------      -----------
     Net interest income after provision for loan losses           13,093            2,977             4,833           20,903
                                                              -----------      -----------       -----------      -----------

Noninterest income:
Fees and service charges                                            1,272              242               688            2,202
Insurance commissions                                               1,200                                               1,200
Securities gains/(losses)                                              53                                (38)              15
Other                                                                 681              137               130              948
                                                              -----------      -----------       -----------      -----------
     Total noninterest income                                       3,206              379               780            4,365
                                                              -----------      -----------       -----------      -----------

Noninterest expense:
Salaries and employee benefits                                      6,584            1,192             1,808            9,584
Occupancy expense, net                                                725              139               413            1,277
Equipment expense                                                     803              180                                983
Operational loss                                                      860                                                 860
Other operating expense                                             2,217              671               546            3,434
                                                              -----------      -----------       -----------      -----------
     Total noninterest expense                                     11,189            2,182             2,767           16,138
                                                              -----------      -----------       -----------      -----------

     Income before taxes                                            5,110            1,174             2,846            9,130
Income tax expense                                                  1,656              321               883            2,860
                                                              -----------      -----------       -----------      -----------
     Net income                                               $     3,454      $       853       $     1,963      $     6,270
                                                              ===========      ===========       ===========      ===========
Basic earnings per share                                                       $      0.77       $      1.06      $      0.99
Diluted earnings per share                                                     $      0.76       $      1.06      $      0.98
Basic weighted average shares outstanding                       4,510,918                          1,850,000        6,360,918
Diluted weighted average shares outstanding                     4,522,066                          1,850,000        6,372,066
</TABLE>

(1) USBN acquired Bank of Pullman (BOP) effective October 1, 1997. The purchase
method of accounting was used for the transaction.

See notes to pro forma condensed combined unaudited financial statements.



                                       39


<PAGE>   50





UNITED SECURITY BANCORPORATION AND BANCWEST FINANCIAL CORPORATION PRO FORMA
CONDENSED COMBINED UNAUDITED INCOME STATEMENT FOR THE YEAR ENDED DECEMBER 31,
1995

<TABLE>
<CAPTION>
($ in thousands, except per share)                                                                                PRO FORMA
Interest Income:                                                 USBN             BOP(1)             BFC           COMBINED
                                                              -----------      -----------       -----------      -----------
<S>                                                           <C>              <C>               <C>              <C>        
Interest and fees on loans and leases                         $    16,514      $     3,551       $     5,471      $    25,536
Interest on securities                                              1,947            1,019             1,162            4,128
Other interest income                                                 491              127                                618
                                                              -----------      -----------       -----------      -----------
     Total interest income                                         18,952            4,697             6,633           30,282
                                                              -----------      -----------       -----------      -----------

Interest expense:
Interest on deposits                                                7,486            1,930             2,476           11,892
Interest on borrowings                                                119               32                95              246
                                                              -----------      -----------       -----------      -----------
     Total interest expense                                         7,605            1,962             2,571           12,138
                                                              -----------      -----------       -----------      -----------

     Net interest income                                           11,347            2,735             4,062           18,144
Provision for loan losses                                             317               65                62              444
                                                              -----------      -----------       -----------      -----------
     Net interest income after provision for loan losses           11,030            2,670             4,000           17,700
                                                              -----------      -----------       -----------      -----------

Noninterest income:
Fees and service charges                                            1,040              235               622            1,897
Insurance commissions                                               1,255                                               1,255
Securities gains/(losses)                                              53                                (5)               48
Life insurance proceeds                                             1,030                                               1,030
Other                                                                 592              106                35              733
                                                              -----------      -----------       -----------      -----------
     Total noninterest income                                       3,970              341               652            4,963
                                                              -----------      -----------       -----------      -----------

Noninterest expense:
Salaries and employee benefits                                      5,477            1,097             1,672            8,246
Occupancy expense, net                                                633              140               419            1,192
Equipment expense                                                     579              207                                786
Death benefit expense                                                 379                                                 379
Other operating expense                                             2,365              676               627            3,668
                                                              -----------      -----------       -----------      -----------
     Total noninterest expense                                      9,433            2,120             2,718           14,271
                                                              -----------      -----------       -----------      -----------

     Income before taxes                                            5,567              891             1,934            8,392
Income tax expense                                                  1,489              265               515            2,269
                                                              -----------      -----------       -----------      -----------
     Net income                                               $     4,078      $       626       $     1,419      $     6,123
                                                              ===========      ===========       ===========      ===========
Basic earnings per share                                                       $      1.04       $      0.77      $      1.06
Diluted earnings per share                                                     $      1.04       $      0.77      $      1.06
Basic weighted average shares outstanding                       3,909,609                          1,850,000        5,759,609
Diluted weighted average shares outstanding                     3,909,609                          1,850,000        5,759,609
</TABLE>

(1) USBN acquired Bank of Pullman (BOP) effective October 1, 1997. The purchase
method of accounting was used for the transaction.

See notes to pro forma condensed combined unaudited financial statements.



                                       40


<PAGE>   51



NOTES TO PRO FORMA CONDENSED COMBINED UNAUDITED FINANCIAL STATEMENTS

1.       ADJUSTMENTS

         The pro forma combined unaudited statement of financial condition
reflects the assumed issuance of 1,850,000 shares of USBN common stock, to BFC
stockholders using the exchange ratio of 4.7. These shares were derived using
the respective outstanding shares of BFC at September 30, 1998. Total
consideration to BFC stockholders was assumed to be $33.3 million.

         The issuance of shares for the Merger is based upon an exchange ratio
of 4.7 resulting from an assumed average closing price for USBN stock of $18.00
per share and that 393,300 outstanding shares including options are outstanding
and subject to exchange on the Effective Date. This assumption is made solely
for the purpose of calculating the pro forma data and is not intended to be a
representation or approximation of the actual exchange ratio.

2.       BASIC AND DILUTED EARNINGS PER SHARE

         Basic and diluted earnings per share is computed on the weighted
average number of basic and diluted common shares outstanding during the periods
presented. Diluted common shares outstanding include common stock equivalents
computed using the treasury stock method. Common stock equivalents include
shares issuable upon exercise of common stock options. Pro forma basic and
diluted earnings per share for the periods presented is computed based on the
respective exchange ratio for BFC common stock described in Note 1. Pro forma
basic and diluted earnings per share amounts may vary due to potential changes
in the exchange ratio.



                                       41



<PAGE>   52



                     BUSINESSES OF THE PARTIES TO THE MERGER

INFORMATION CONCERNING USBN

         USBN. USBN is a multi-bank holding company headquartered in Spokane,
Washington. USBN owns four banks, United Security Bank, a Washington bank; Home
Security Bank, a Washington bank; Grant National Bank, a national bank and Bank
of Pullman, an Idaho bank, and also owns USB Insurance (an insurance agency),
USB Leasing (a leasing company), and USB Mortgage (a mortgage company). Each of
USBN's nonbank subsidiaries are Washington corporations. The principal executive
offices of USBN are located at 9506 North Newport Highway, Spokane, Washington
99218-1200 and its telephone number is (509) 467-6949.

         USBN conducts its banking business through 27 branches located in
communities throughout eastern Washington, including Spokane and a branch in
Moscow, Idaho. USBN focuses its banking and other services on individuals,
professionals, and small to medium-sized businesses in diversified industries
throughout its service area. At September 30, 1998, USBN had total consolidated
assets of $404.7 million, net loans of $285.0 million and deposits of $354.8
million. USBN was founded in 1983 and has been profitable in every year since
its inception. Additional information concerning USBN, including financial
information and information relating to USBN's directors and executive officers,
is included in the USBN documents incorporated by reference in this
Prospectus/Joint Proxy Statement. See "INFORMATION INCORPORATED BY REFERENCE"
and "WHERE YOU CAN FIND MORE INFORMATION."

         Year 2000 Issue. The Year 2000 Problem. The century date change creates
a problem because some computer programs and systems were designed to store
calendar years with only two numbers, rather than four numbers. Computer
programs and systems may recognize a date using "00" as 1900 rather than the
Year 2000. The extent of the impact of this Year 2000 problem is not yet known
and could affect the global economy and every organization. USBN is addressing
these issues.

         The Challenges Faced by USBN. The Year 2000 problem is of concern to
USBN and other financial institutions because most financial transactions,
including interest accruals and payments, are date sensitive. The Year 2000
problem could impact all automated systems including automated teller machines,
alarm systems, and vaults. Some systems are more difficult to assess and repair.

         USBN's State of Readiness. USBN is reviewing its automated systems and
business processes to identify and correct any date-related problems that may
arise with the change of the century at December 31, 1999. In September, 1998,
USBN and the provider of USBN's mainframe computer applications completed an
installation and upgrade of the mainframe operating systems to comply with
changes for the Year 2000. Testing of the new software will continue through
December 31, 1998. USBN also continues to review its PC hardware and software
and its major automated systems suppliers for Year 2000 compliance. A small
number of PCs and PC systems required upgrades, which has been completed.

         Third Party Concerns. USBN has numerous customers, vendors, and third
part service providers whose failure to address the Year 2000 problem may create
significant business disruption and costs to USBN. It is impossible for any one
party to eliminate the risks related to the Year 2000 problem. It is possible
that USBN's service could be disrupted through the loss of electric power, phone
service, or other reasons outside of USBN's control. USBN is in contact with its
outside providers of services on an ongoing basis to evaluate their progress in
addressing their Year 2000 problem.

         USBN's banking subsidiaries are incorporating Year 2000 issues into
their standards of creditworthiness for new and renewed loans and are reviewing
significant existing borrowers for Year 2000 risk. Review in this area will
continue through 1999.



                                       42

<PAGE>   53


         Estimated Costs. Based on USBN's current analysis, the cost of
complying with the Year 2000 issues is estimated to be approximately $175,000
including staff time expenses. About $100,000 of this amount has already been
incurred.

         USBN's Contingency Plans. USBN is in the process of developing and
implementing contingency plans to handle the most reasonably likely worst case
scenarios. Since these worst case scenarios are difficult or even impossible to
predict at this time, these contingency plans are particularly challenging. USBN
intends to develop contingency plans that are reasonably necessary to address
the Year 2000 problem and to revise them as necessary on an ongoing basis until
the problem is confronted and resolved.

                           FORWARD LOOKING STATEMENTS

         The discussion above regarding to the century date change for the year
2000 includes certain "forward looking statements" concerning the future
operations of USBN. USBN desires to take advantage of the "safe harbor"
provisions of the Private Securities Litigation Reform Act of 1995 as they apply
to forward looking statements. This statement is for the express purpose of
availing USBN of the protections of such safe harbor with respect to all
"forward looking statements." Management's ability to predict results of the
effect of future plans is inherently uncertain, and is subject to factors that
may cause actual results to differ materially from those projected. Factors that
could affect the actual results include USBN's success in identifying systems
and programs that are not Year 2000 compliant; the possibility that systems
modifications will not operate as intended; unexpected costs associated with
remediation, including labor and consulting costs; the nature and amount of
programming required to upgrade or replace the affected systems; the uncertainty
associated with the impact of the century change on USBN's customers, vendors
and third-party service providers, and the economy generally.

INFORMATION CONCERNING BFC

         Business. BFC, a Washington corporation, was organized in 1994 for the
purpose of becoming the holding company for the Bank. BFC engages in no
significant activity other than holding the stock of the Bank.

         The Bank was incorporated in 1976 as a state chartered bank under the
laws of the State of Washington, and conducts a commercial banking business in
Walla Walla and Columbia Counties. The Bank primarily serves individuals and
small-to-medium-sized businesses and offers a full range of deposit services
that are typically available in most financial institutions, including checking
accounts, savings accounts and other time deposits of various types, ranging
from money market accounts to longer term certificates of deposit. The
transaction accounts and time certificates are tailored to the principal market
areas at rates competitive in the area. In addition, retirement accounts such as
IRAs (Individual Retirement Accounts) are available. The Bank attracts deposits
primarily from individuals, merchants, small and medium sized businesses and
professionals. The FDIC insures deposit accounts up to the maximum amount.

         The principal source of the Bank's revenues are: (i) interest and fees
on loans; (ii) deposit service charges; (iii) merchant credit card processing
fees; (iv) federal funds sold (funds loaned on a short-term basis to other
banks); and (v) interest on investments (principally government securities). The
Bank's lending activity consists of short-to-medium-term commercial and consumer
loans, including operating loans and lines, equipment loans, automobile loans,
recreational vehicle and truck loans, personal loans or lines of credit, home
improvement and rehabilitation loans and credit cards. The Bank also offers cash
management services, merchant credit card processing, safe deposit boxes, wire
transfers, direct deposit or payroll and Social Security checks, automated
teller machine access, and automatic drafts for various accounts.

         Competition. The geographic market area served by the Bank is highly
competitive with respect to both loans and deposits. The Bank competes
principally with commercial banks, savings and loan associations, credit 



                                       43

<PAGE>   54


unions, mortgage companies, and other financial institutions. The major
commercial bank competitors are the regional banks that have a branch or
branches within the Bank's primary trade areas. Among the advantages such larger
banks have are their ability to finance wide-ranging advertising campaigns and
to allocate their investment assets to geographic regions of higher yield and
demand. Such banks offer certain services which are not offered directly by the
Bank (but are offered indirectly through correspondent institutions); and, by
virtue of their greater total capitalization, such banks have substantially
higher lending limits than the Bank.

         In order to compete with the other financial institutions in their
primary trade areas, the Bank uses, to the fullest extent possible, the
flexibility which is accorded by its independent status. This includes an
emphasis on specialized services, local promotional activity, and personal
contacts by the Bank's officers, directors and employees. The Bank also provides
special services and programs for individuals in their primary trade areas who
are employed in the business and professional fields.

         Facilities. The Bank conducts its business through four full-service
offices. All premises are owned by the Bank and include vaults with safe deposit
boxes. The Bank's main office is located at 30 West Main Street in downtown
Walla Walla and also serves as the main office for the holding company. The main
office has approximately 36,000 square feet in an historic building with a two
lane drive-up facility unattached from the main building. The main branch was
remodeled during the last three years. The Eastgate branch, also located in
Walla Walla at 1969 Walla Walla Avenue, serves as the Bank's main vault for
cash, currency and safe deposit boxes. It has approximately 4,000 square feet of
space, a two lane drive-up facility and was refurbished in 1995. The Bank's
branch in Dayton is located at 427 East Main Street and has approximately 3,300
square feet of space and a full basement. The Dayton branch was built in 1995
and has a two lane drive-up facility. The Waitsburg branch is located at 215
Main Street and has approximately 5,000 square feet of space. It was refurbished
in 1998 and has a new single lane drive-up facility.

         Employees. BFC and the Bank have a total of 43 full-time equivalent
employees and 10 part-time equivalent employees. None of the employees is
subject to a collective bargaining agreement. The Bank considers its
relationships with its employees to be good.

         The Year 2000 Problem. The century date change creates a problem
because computer programs and systems were designed to store calendar years with
only two numbers, rather than four numbers. Because of this faulty design,
computer programs and systems may recognize a date using "00" as 1900 rather
than the Year 2000. The extent of the potential impact of this Year 2000 problem
is not yet known and could affect the global economy and every organization.

         Only one thing is certain about the impact of the Year 2000--it is
difficult to predict with any degree of certainty what will happen after
December 31, 1999. BFC is committed to address and is addressing these Year 2000
issues and the uncertainty that is presented by these Year 2000 issues. The
total financial effect that the Year 2000 problem will have on BFC is uncertain
and will not be known until the year 2000 arrives. In spite of BFC's efforts to
mitigate the Year 2000 problem, the success of BFC's efforts will not be known
until the year 2000 arrives.

         The Challenges faced by BFC: The Year 2000 problem is of particular
concern to BFC and other financial institutions because most financial
transactions, such as interest accruals and payments, are date sensitive. The
Year 2000 problem will impact both information technology ("IT") systems, such
as computers, and non-IT systems. Non-IT systems typically include embedded
technology such as microcontrollers, and include automated teller machines,
elevators, alarm systems, and vaults. Non-IT systems are more difficult to
assess and repair than IT systems.




                                       44

<PAGE>   55


         BFC's State of Readiness: BFC established a Year 2000 Committee with
representatives from all significant functional areas which report to the BFC
Board of Directors. Detailed inventories for all IT systems and all identified
non-IT systems have been conducted to catalog potential hardware and software
problems. BFC has identified certain systems as business-critical systems and
testing of those business-critical systems has commenced. BFC has identified the
end of this year as the projected deadline to complete the Year 2000 testing on
business-critical systems. Testing will continue into the year 1999 for those
business-critical systems that are not tested in 1998 and for those systems that
have not been identified as critical. BFC has determined that modifications to
certain systems are required and that such modifications will be conducted to
mitigate, but not eliminate, the risks associated with the Year 2000 problem.

         Third Party Concerns: BFC interacts with numerous customers, vendors
and third party service providers whose failure to address the Year 2000 problem
may create significant business disruption and costs to BFC. Due to the
interdependence of computer systems today, it is simply impossible for any one
party to eliminate the risks related to the Year 2000 problem. It is even
possible that the Year 2000 problem could disrupt BFC's business through the
loss of electric power or phone service, or for other reasons outside of BFC's
control. BFC has initiated formal communications with certain significant
suppliers and large customers to attempt to determine the extent to which BFC is
vulnerable to those third parties' failure to remediate their own Year 2000
issues. Systems of other companies on which BFC's systems rely may not be timely
converted, which might well result in significant costs to BFC.

         BFC is in the process of assessing the incremental credit risk in loan
portfolio relating to individual customers' ability to successfully address Year
2000 IT and non-IT issues. For those over an established dollar threshold,
credit risk assessments are being or will be performed on each borrower. This
process will be ongoing until the Year 2000.

         Estimated Costs: It is impossible to predict with any degree of
certainty the costs that BFC will incur as a result of the Year 2000 problem.
BFC's current estimate for the total year 2000 testing and remediation is
roughly $200,000, which will be funded through cash flows of operations. BFC has
incurred and expensed approximately $60,000 addressing the Year 2000 problem.
These future financial estimates are just rough estimates. There are risks and
uncertainties that may cause future results to differ materially. It is
uncertain to what extent the actual costs of the Year 2000 problem will have on
BFC's results of operations, liquidity, and financial condition. Actual lost
revenue resulting from the Year 2000 problem is impossible to predict because of
the inherent uncertainty of the Year 2000 problem. BFC, through its Year 2000
Committee, is analyzing and determining how to best handle and mitigate this
uncertainty. BFC presently believes that costs associated with compliance
efforts will not have a significant impact on BFC's ongoing operations, although
there can be no assurance in this regard.

         BFC's Contingency Plans: The Year 2000 Committee is in the process of
developing and implementing contingency plans to handle the most reasonably
likely worst case scenarios. Since these worst case scenarios are difficult or
even impossible to predict at this time, these contingency plans are
particularly challenging. BFC intends to develop contingency plans that are
reasonably necessary to address the Year 2000 problem and to revise those
contingency plans on an ongoing basis until the problem is confronted and
resolved.

         Legal Proceedings. The Bank is from time to time party to various legal
actions arising in the normal course of business. The Bank believes that there
is no threatened or pending proceeding against it, which, if determined
adversely, would have a material effect on the business or financial position of
the Bank.



                                       45

<PAGE>   56


      SECURITY OWNERSHIP OF CERTAIN BENEFICIAL OWNERS AND MANAGEMENT OF BFC

         The following table sets forth the shares of BFC common stock
beneficially owned as of the BFC record date by each person who, to the
knowledge of BFC, owns more than five percent of its outstanding shares, by each
director of BFC, by the Chief Executive Officer of BFC, and by all executive
officers and directors as a group.

<TABLE>
<CAPTION>
                                     SHARES BENEFICIALLY             % OF TOTAL SHARES
NAME                                       OWNED(1)                     OUTSTANDING
----                                 -------------------             -----------------
<S>                                         <C>                             <C>  
Wesley Colley(2)(3)                         43,423                          11.8%
Harold Cochran(4)                            7,834                           2.1%
David Frame(5)                              26,485                           7.2%
Mark Graves(6)                               6,161                           1.7%
Allen Ketelson(7)                            1,994                           0.5%
Norman McKibben                             13,996                           3.8%
Directors and Executive
Officers(8) as a group                     111,857                          28.5%
</TABLE>

----------

(1)      In accordance with Rule 13d-3 under the Exchange Act, a person is
         deemed to be the beneficial owner, for purposes of this table, of any
         share of BFC common stock if he or she has voting and/or investment
         power with respect to such security. The table includes shares owned by
         spouses, other immediate family members in trust, shares held in
         retirement accounts or funds for the benefit of the named individuals,
         and other forms or ownership, over which shares the persons named in
         the table possess voting and/or investment power. The amounts shown
         also include shares of BFC common stock which each indicated individual
         has the right to acquire within 60 days of the BFC record date through
         the exercise of stock options granted pursuant to BFC's stock option
         plans.

(2)      Mr. Colley is the Chief Executive Officer of BFC.

(3)      Includes 3,423 shares subject to stock options granted pursuant to the
         BFC stock option plans.

(4)      Includes 3,824 shares subject to stock options granted pursuant to the
         BFC stock option plans.

(5)      Includes 3,824 shares subject to stock options granted pursuant to the
         BFC stock option plans. Also includes 7,011 shares owned by American
         Linebuilders Trust Account, of which Mr. Frame has voting control.

(6)      Includes 2,864 shares subject to stock options granted pursuant to the
         BFC stock option plans.

(7)      Includes 1,344 shares subject to stock options granted pursuant to the
         BFC stock option plans.



                                       46

<PAGE>   57



                   BFC MANAGEMENT'S DISCUSSION AND ANALYSIS OF
                  FINANCIAL CONDITION AND RESULTS OF OPERATIONS

         The discussion presented below analyzes major factors and trends
regarding the financial condition and results of BFC's operations for the nine
months ended September 30, 1998 and 1997 and for the years ended December 31,
1997 and 1996. BFC engages in no significant activity other than holding the
stock of the Bank. The Bank is a state chartered bank and operates four offices,
two located in Walla Walla and one each located in Waitsburg and Dayton,
Washington. The Bank's primary source of revenue is derived from providing loans
to customers, who are predominantly small and middle market businesses and
middle-income individuals. A substantial portion of the Bank's loan portfolio
represents loans to customers directly or indirectly involved in the
agribusiness industry in the region served by the Bank.

FINANCIAL CONDITIONS AND RESULTS OF OPERATIONS FOR THE NINE MONTHS ENDED
SEPTEMBER 30, 1998 AND 1997

         Overview. The Bank's total assets of $104,100,000 at September 30, 1998
represents a 3% increase over total assets of $100,900,000 at September 30,
1997. Most of this net increase resulted from increases in loans. The growth was
funded primarily by increases in deposits and retained earnings.

         Net Income. For the nine months ended September 30, 1998 and 1997, net
income was $1,659,000 and $1,660,000, respectively. Basic earnings per share for
the nine month periods ended September 30, 1998 and 1997, were $4.57 and $4.69,
respectively.

         Net Interest Income. Net interest income for the nine months ended
September 30, 1998 was $4,091,000, an increase of $267,000 or 7.0% compared to
the nine months ended September 30, 1997. This increase resulted primarily from
an increase in earning assets (primarily loans) during the period, less the
effect of an increase in interest-bearing liabilities.

FINANCIAL CONDITIONS AND RESULTS OF OPERATIONS FOR THE YEARS ENDED DECEMBER 31,
1997 AND 1996

         Overview. The Bank's total assets of $102,500,000 at December 31, 1997,
represent a $9,000,000, or 9.6% increase over total assets of $93,500,000 at
December 31, 1996. Most of the growth is a result of increases in loans and
securities primarily funded by increases in deposits and retained earnings.

         Net Income. For the years ended December 31, 1997 and 1996, the Bank's
net income was $1,931,000 and $1,963,000, respectively, a decrease of $32,000 in
1997 compared with 1996. The decrease is due to an increase in noninterest
expense and provision for loan losses. Noninterest expense grew with normal
operational activity. The provision for loan losses was due to a normal review
of the loan portfolio. Basic earnings per share for the years ended December 31,
1997 and 1996, were $5.46 and $5.61, respectively.

         Net Interest Income. Net interest income of $5,132,000 for the year
ended December 31, 1997, increased $299,000 or 6.2% compared to $4,833,000 for
the year ended December 31, 1996. The increase in net interest income was
primarily due to increases in the Bank's earning assets, particularly its loan
and securities portfolios. The Bank's net yield on earning assets totaled 5.88%
and 5.96% for the years ended December 31, 1997 and 1996.

         Non-Interest Expenses. Non-interest expenses for the year ended
December 31, 1997, increased $124,000, or 4.5% from the year ended December 31,
1996. The increase was primarily related to an increase in employee compensation
and data processing fees.



                                       47

<PAGE>   58


LOAN QUALITY, LIQUIDITY AND CAPITAL

         Overview. Loans, net of allowance, totaled $70,345,000 at September 30,
1998 as compared to $66,268,000 at December 31, 1997 and $59,644,000 at December
31, 1996. The Bank's loan growth of $7,017,000, or 11.7% from 1996 to 1997 can
be attributed to increased loan demand and market conditions, particularly in
the Dayton area. Agriculture and commercial loans represent the largest portion
of this increase.

         Allowance for Loan Losses. The allowance for loan losses represents
management's current estimate of amounts required to absorb credit losses on
existing loans. The allowance of $865,000 at September 30, 1998 and $1,004,000
at December 31, 1997, is an increase from the $611,000 allowance at December 31,
1996. The allowance represents 1.21% of loans at September 30, 1998 and 1.49% at
December 31, 1997, as compared to 1.01% at December 31, 1996.

         The allowance for loan losses is increased by provisions charged to
operations and reduced by loans charged off, net of recoveries. The allowance is
based on management's periodic evaluation of potential losses in the portfolio
after consideration of historical loss experience, adverse situations that may
affect the borrower's ability to repay, the estimated value of any collateral,
economic conditions, and other risk inherent in the portfolio.

         The following table presents an analysis of the Bank's loan loss
experience for the years ended December 31, 1997 and 1996:

                      ANALYSIS OF ALLOWANCE FOR LOAN LOSSES
                                 (in thousands)

<TABLE>
<CAPTION>
                                                             Years Ended December 31,
                                                             ------------------------
                                                                 1997          1996
                                                                -------       -------
<S>                                                             <C>           <C>    
Balance, beginning of year                                      $   611       $   560

Loans charged off:
         Real Estate Loans                                      $     0       $     0
         Installment Loans                                      $    38       $    20
         Credit Cards                                           $    13       $     0
         Commercial Loans                                       $    73       $   105
                                                                -------       -------
         Total Charge-Offs                                      $   124       $   125

Recoveries:
         Real Estate Loans                                      $     0       $     0
         Installment Loans                                      $     7       $     3
         Credit Cards                                           $     0       $     0
         Commercial Loans                                       $   207       $   173
                                                                -------       -------
         Total Recoveries                                       $   214       $   176

Net (charge-offs) Recoveries                                    $    90       $   (51)

Provision charged to operations                                 $   303       $     0

Balance, end of year                                            $ 1,004       $   611

Ratio of net charge-offs (recoveries) during the year to           (.17)         (.09)
average loans outstanding during the year
</TABLE>



                                       48


<PAGE>   59


         Liquidity and Sources of Funds. The Bank's primary sources of funds are
customer deposits, loan repayments, net income, and deposits and/or loans from
the Federal Home Loan Bank of Seattle (FHLB), as well as their correspondent
bank lines. Scheduled loan repayments are a relatively stable source of funds
while deposit inflows and unscheduled loan prepayments are influenced by general
interest rate levels, interest rates on other investment, competition, economic
conditions and other factors.

         Total deposits were approximately $87.3 million of December 31, 1997,
up $4.9 million from December 31, 1996 balance of $82.4 million. The Bank does
not accept brokered deposits. A concerted effort has been made to attract
deposits in the market area the Bank serves through competitive pricing and
delivery of quality products.

         Capital. The Tier 1 capital-to-asset ratio for the Bank was 12.6% at
December 31, 1997 compared to 13.6% at December 31, 1996. This ratio was
impacted by good growth in assets and a cash dividend that was declared in 1996.
The Tier 1 capital-to-risk-weighted-asset ratio was 11.4% at December 31, 1997
and 12.9% at December 31, 1996.

         Risk Elements. Risk elements include accruing loans past due 90 days or
more, non-accrual loans, and loans that have been restructured to provide a
reduction or deferral of interest or principal for reasons related to the
borrower's financial potential problem loans, and loan concentrations. The
following table states the Bank's non-accrual loans as of September 30, 1998,
December 31, 1997, and December 31, 1996. There were no restructured loans on
these dates.

<TABLE>
<CAPTION>
                                                                   December 31,
                                                           ------------------------------
                                  September 30, 1998         1997                1996
                                  ------------------       --------           -----------
<S>                                    <C>                 <C>                 <C>     
Non accrual loans                      $      0            $      0            $     0
Loans accruing past 90 days            $766,000            $218,000            $52,000
</TABLE>


         The accrual of interest on loans is discontinued when, in management's
opinion, the borrower may be unable to meet payment requirements as they become
due. When interest accrual is discontinued, all unpaid accrued interest is
reversed against current interest income. Interest income is subsequently
recognized only to the extent payments are received.

         At September 30, 1998, the Bank was not aware of any loans that should
not continue to accrue interest or that management reasonably expects will have
a materially negative impact on future operating results. The Bank's management
is not aware of any information concerning any material loans, other than those
discussed as risk elements above, that cause it to have doubts as to the ability
of the borrowers to comply with the terms of the loans.

QUANTITATIVE AND QUALITATIVE DISCLOSURE ABOUT MARKET RISK

         Market risk is considered by the Bank's management to be the exposure
to loss resulting from changes in interest rates (interest rate risk). The
Bank's interest rate risk arises from the instruments and transactions entered
into for purposes other than trading. They include loans, investment securities,
and deposit liabilities. All of the Bank's financial instruments and
transactions are denominated in U.S. dollars. The Bank does not use derivative
financial instruments for management of market risk or asset/liability
management. Interest rate risk occurs when assets and liabilities pre-price at
different times as interest rates change. The Bank's interest rate risk
management includes supervision of the board's ALCO committee, a board policy on
interest rate risk, and monthly review and monitoring of the amount of interest
rate risk being taken by the Bank. By policy the Bank's earnings exposure is
limited due to interest rate risk by setting limits on positive and negative
gaps within the 




                                       49

<PAGE>   60


next 12 months. These limits are set so that previous years' profits will not be
unduly impacted should interest rates change during the year. Approximately 59%
of the Bank's loan portfolio consists of loans having floating interest rates.
Fixed rate loans are generally made within a term of five years or less.

         The following table discloses the balances of financial instruments
including the fair value as of December 31, 1997. The expected maturities are
stated final dates and do not take into consideration historical and estimated
principal prepayments for loans and securities. The roll-off rates for
non-interest bearing deposits, interest-bearing demand deposits and savings
deposits are 15%, 25% and 20%, respectively. The interest rates disclosed are
based on rates from 1997 results. Fair values are based on calculations used in
accordance with generally accepted accounting principals.

                               EXPECTED MATURITIES

                                ($ IN THOUSANDS)

(YEAR ENDED DECEMBER 31, 1997)

<TABLE>
<CAPTION>
                                                                                                    THERE-                  FAIR
                                        1998         1999        2000         2001       2002       AFTER       TOTAL       VALUE
                                      -------        -----       -----       -----       -----      ------     -------     --------
<S>                                   <C>            <C>         <C>         <C>         <C>        <C>         <C>         <C>   
FINANCIAL ASSETS
Cash & due from banks                 $ 3,070                                                                  $ 3,070     $ 3,070
Overnight funds                             0
Securities                              2,449        2,089       2,698       2,778       1,027      18,340      29,381      29,476
   Weighted average interest rate                                                                                 6.83%
Fixed rate loans                        3,789        3,843       3,843       3,843       3,844       9,154      28,316      29,054
   Weighted average interest rate                                                                                 9.87%
Variable rate loans                    24,541        2,000       2,486       2,676       6,637         616      38,956      38,956
   Weighted average interest rate                                                                                10.08%
FINANCIAL LIABILITIES
Noninterest bearing deposits            2,759        2,759       2,759       2,759       2,759       4,586      18,381      18,381
Interest bearing demand deposits        1,764        1,764       1,764       1,762           0           0       7,054       7,054
   Weighted average interest rate                                                                                 1.67%
Savings Deposits                        4,540        4,540       4,540       4,540       4,541           0      22,701      22,701
   Weighted Average interest rate                                                                                 3.62%
Time deposits                          33,085        4,777         502         365         425           0      39,154      39,154
   Weighted average interest rate                                                                                 5.43%
Borrowed funds                          4,295                                                                    4,295       4,295
   Weighted average interest rate                                                                                 5.40%
</TABLE>

         The above table presents information about the Bank's interest
sensitivity, it does not predict future earnings. The Bank uses budgeting and
earnings projections to forecast earnings under different interest rate
projections. It requires significant assumptions about the projection of loan
prepayments, loan origination's and liability funding sources, which may be
inaccurate. Weighted average interest rates by expected maturity is not
available.



                                       51

<PAGE>   61


                           SUPERVISION AND REGULATION

INTRODUCTION

         The following generally refers to certain statutes and regulations
affecting the banking industry. These references provide brief summaries only
and are not intended to be complete. They are qualified in their entirety by the
referenced statutes and regulations. In addition, some statutes and regulations
may exist which apply to and regulate the banking industry, but are not
referenced below.

         USBN is a bank holding company, due to its ownership of United Security
Bank, Home Security Bank, Bank of Pullman and Grant National Bank (collectively,
the "Subsidiaries"). The Bank Holding Company Act of 1956, as amended ("BHCA")
subjects USBN and the Subsidiaries, as well as BFC and the Bank, to supervision
and examination by the Federal Reserve Bank ("FRB"), and USBN and BFC file
annual reports of operations with the FRB.

BANK HOLDING COMPANY REGULATION

         In general, the BHCA limits bank holding company business to owning or
controlling banks and engaging in other banking-related activities. Bank holding
companies must obtain the FRB's approval before they: (1) acquire direct or
indirect ownership or control of any voting shares of any bank that results in
total ownership or control, directly or indirectly, of more than 5% of the
voting shares of such bank; (2) merge or consolidate with another bank holding
company; or (3) acquire substantially all of the assets of any additional banks.
Subject to certain state laws, such as age and contingency laws, a bank holding
company that is adequately capitalized and adequately managed may acquire the
assets of both in-state and out-of-state bank.

         Control of Nonbanks. With certain exceptions, the BHCA prohibits bank
holding companies from acquiring direct or indirect ownership or control of
voting shares in any company that is not a bank or a bank holding company unless
the FRB determines that the activities of such company are incidental or closely
related to the business of banking. If a bank holding company is
well-capitalized and meets certain criteria specified by the FRB, it may engage
de novo in certain permissible nonbanking activities without prior FRB approval.

         Control Transactions. The Change in Bank Control Act of 1978, as
amended, requires a person (or group of persons acting in concert) acquiring
"control" of a bank holding company to provide the FRB with 60 days' prior
written notice of the proposed acquisition. Following receipt of this notice,
the FRB has 60 days within which to issue a notice disapproving the proposed
acquisition, but the FRB may extend this time period for up to another 30 days.
An acquisition may be completed before expiration of the disapproval period if
the FRB issues written notice of its intent not to disapprove the transaction.
In addition, any "company" must obtain the FRB's approval before acquiring 25%
(5% if the "company" is a bank holding company) or more of the outstanding
shares or otherwise obtaining control over USBN or BFC.

TRANSACTIONS WITH AFFILIATES

         USBN and the Subsidiaries are deemed affiliates within the meaning of
the Federal Reserve Act, and transactions between affiliates are subject to
certain restrictions. Accordingly, USBN and the Subsidiaries must comply with
Sections 23A and 23B of the Federal Reserve Act. Generally, Sections 23A and 23B
(1) limit the extent to which the financial institution or its subsidiaries may
engage in "covered transactions" with an affiliate, as defined, to an amount
equal to 10% of such institution's capital and surplus and an aggregate limit on
all such transactions with all affiliates to an amount equal to 20% of such
capital and surplus, and (2) require all transactions with an affiliate, whether
or not "covered transactions," to be on terms substantially the same, or at
least as favorable to the institution or subsidiary, as those provided to a
non-affiliate. The term "covered 



                                       51

<PAGE>   62


transaction" includes the making of loans, purchase of assets, issuance of a
guarantee and other similar types of transactions.

REGULATION OF MANAGEMENT

         Federal law (1) sets forth the circumstances under which officers or
directors of a financial institution may be removed by the institution's federal
supervisory agency; (2) places restraints on lending by an institution to its
executive officers, directors, principal stockholders, and their related
interests; and (3) prohibits management personnel from serving as a director or
in other management positions with another financial institution which has
assets exceeding a specified amount or which has an office within a specified
geographic area.

TIE-IN ARRANGEMENTS

         USBN and the Subsidiaries cannot engage in certain tie-in arrangements
in connection with any extension of credit, sale or lease of property or
furnishing of services. For example, with certain exceptions, neither USBN nor
the Subsidiaries may condition an extension of credit on either (1) a
requirement that the customer obtain additional services provided by it or (2)
an agreement by the customer to refrain from obtaining other services from a
competitor.

         The FRB has adopted significant amendments to its anti-tying rules
that: (1) removed FRB-imposed anti-tying restrictions on bank holding companies
and their non-bank subsidiaries; (2) allow banks greater flexibility to package
products with their affiliates; and (3) establish a safe harbor from the trying
restrictions for certain foreign transactions. These amendments were designed to
enhance competition in banking and nonbanking products and to allow banks and
their affiliates to provide more efficient, lower cost service to their
customers. However, the impact of the amendments on USBN and the Subsidiaries is
unclear at this time.

STATE LAW RESTRICTIONS

         As Washington corporations, USBN and BFC may be subject to certain
limitations and restrictions as provided under applicable Washington corporate
law. Each of the Subsidiaries (except Grant National Bank) and the Bank, as
Washington state-chartered commercial banks, is subject to supervision and
regulation by the Washington Department of Financial Institutions.

THE SUBSIDIARIES

GENERAL

         The Subsidiaries (except Grant National Bank), as well as the Bank, are
subject to extensive regulation and supervision by the Washington Department of
Financial Institutions and the FDIC. Grant National Bank, as a national banking
association, is subject to regulation and examination by the OCC. The federal
laws that apply to USBN's banking subsidiaries and the Bank regulate, among
other things, the scope of their business, their investments, their reserves
against deposits, the timing of the availability of deposited funds and the
nature and amount of and collateral for loans. The laws and regulations
governing the Subsidiaries and the Bank generally have been promulgated to
protect depositors and not to protect stockholders of such institutions or their
holding companies.

         CRA. The Community Reinvestment Act (the "CRA") requires that, in
connection with examinations of financial institutions within their
jurisdiction, the Federal Reserve or the FDIC evaluates the record of the
financial institutions in meeting the credit needs of their local communities,
including low and moderate income 



                                       52

<PAGE>   63


neighborhoods, consistent with the safe and sound operation of those banks.
These factors are also considered in evaluating mergers, acquisitions, and
applications to open a branch or facility.

         Insider Credit Transactions. Banks are also subject to certain
restrictions imposed by the Federal Reserve Act on extensions of credit to
executive officers, directors, principal stockholders, or any related interests
of such persons. Extensions of credit (i) must be made on substantially the same
terms, including interest rates and collateral, and follow credit underwriting
procedures that are not less stringent than those prevailing at the time for
comparable transactions with persons not covered above and who are not
employees; and (ii) must not involve more than the normal risk of repayment or
present other unfavorable features. Banks are also subject to certain lending
limits and restrictions on overdrafts to such persons. A violation of these
restrictions may result in the assessment of substantial civil monetary
penalties on the affected bank or any officer, director, employee, agent, or
other person participating in the conduct of the affairs of that bank, the
imposition of a cease and desist order, and other regulatory sanctions.

         FDICIA. Under the Federal Deposit Insurance Corporation Improvement Act
(the "FDICIA"), each federal banking agency has prescribed, by regulation,
noncapital safety and soundness standards for institutions under its authority.
These standards cover internal controls, information systems, and internal audit
systems, loan documentation, credit underwriting, interest rate exposure, asset
growth, compensation, fees and benefits, such other operational and managerial
standards as the agency determines to be appropriate, and standards for asset
quality, earnings and stock valuation. An institution which fails to meet these
standards must develop a plan acceptable to the agency, specifying the steps
that the institution will take to meet the standards. Failure to submit or
implement such a plan may subject the institution to regulatory sanctions.
Management of USBN and BFC believe that the Subsidiaries and the Bank meet all
such standards, and therefore, does not believe that these regulatory standards
materially affect USBN's or BFC's business operations.

INTERSTATE BANKING AND BRANCHING

         The Riegle-Neal Interstate Banking and Branching Efficiency Act of 1994
(the "Interstate Act") permits nationwide interstate banking and branching under
certain circumstances. This legislation generally authorizes interstate
branching and relaxes federal law restrictions on interstate banking. Currently,
bank holding companies may purchase banks in any state, and states may not
prohibit such purchases. Additionally, banks are permitted to merge with banks
in other states as long as the home state of neither merging bank has opted out.
The Interstate Act requires regulators to consult with community organizations
before permitting an interstate institution to close a branch in a low-income
area.

         Under recent FDIC regulations, banks are prohibited from using their
interstate branches primarily for deposit production. The FDIC has accordingly
implemented a loan-to-deposit ratio screen to ensure compliance with this
prohibition.

         With regard to interstate bank mergers, Washington has "opted-in" to
the Interstate Act and allows in-state banks to merge with out-of-state banks
subject to certain aging requirements. Washington law generally authorizes the
acquisition of an in-state bank by an out-of-state bank holding company through
the acquisition of a financial institution if the in-state bank being acquired
has been in existence for at least 5 years prior to the acquisition. At this
time, the full impact that the Interstate Act might have on USBN and BFC is
impossible to predict.




                                       53

<PAGE>   64


DEPOSIT INSURANCE

         The deposits of the Subsidiaries and of the Bank are currently insured
to a maximum of $100,000 per depositor through the Bank Insurance Fund ("BIF")
administered by the FDIC. All insured banks are required to pay semi-annual
deposit insurance premium assessments to the FDIC.

         The FDICIA included provisions to reform the Federal Deposit Insurance
System, including the implementation of risk-based deposit insurance premiums.
The FDICIA also permits the FDIC to make special assessments on insured
depository institutions in amounts determined by the FDIC to be necessary to
give it adequate assessment income to repay amounts borrowed from the U.S.
Treasury and other sources, or for any other purpose the FDIC deems necessary.
The FDIC has implemented a risk-based insurance premium system under which banks
are assessed insurance premiums based on how much risk they present to the BIF.
Banks with higher levels of capital and a low degree of supervisory concern are
assessed lower premiums than banks with lower levels of capital or a higher
degree of supervisory concern.

DIVIDENDS

         The principal source of USBN's cash revenues is dividends received from
the Subsidiaries. The payment of dividends is subject to government regulation,
in that regulatory authorities may prohibit banks and bank holding companies
from paying dividends which would constitute an unsafe or unsound banking
practice. In addition, a bank may not pay cash dividends if that payment could
reduce the amount of its capital below that necessary to meet minimum applicable
regulatory capital requirements. Other than the laws and regulations noted
above, which apply to all banks and bank holding companies, neither USBN, BFC,
the Subsidiaries or the Bank is currently subject to any regulatory restrictions
on its dividends.

CAPITAL ADEQUACY

         Federal bank regulatory agencies use capital adequacy guidelines in the
examination and regulation of bank holding companies and banks. If capital falls
below minimum guideline levels, the holding company or bank may be denied
approval to acquire or establish additional banks or nonbank businesses or to
open new facilities.

         The FDIC and Federal Reserve use risk-based capital guidelines for
banks and bank holding companies. These are designed to make such capital
requirements more sensitive to differences in risk profiles among banks and bank
holding companies, to account for off-balance sheet exposure and to minimize
disincentives for holding liquid assets. Assets and off-balance sheet items are
assigned to broad risk categories, each with appropriate weights. The resulting
capital ratios represent capital as a percentage of total risk-weighted assets
and off-balance sheet items. The guidelines are minimums, and the Federal
Reserve has noted that bank holding companies contemplating significant
expansion programs should not allow expansion to diminish their capital ratios
and should maintain ratios well in excess of the minimum. The current guidelines
require all bank holding companies and federally-regulated banks to maintain a
minimum risk-based total capital ratio equal to 8%, of which at least 4% must be
Tier I capital. Tier I capital for bank holding companies includes common
stockholders' equity, certain qualifying perpetual preferred stock and minority
interests in equity accounts of consolidated subsidiaries, less intangibles
except as described above.

         The Federal Reserve also employs a leverage ratio, which is Tier I
capital as a percentage of total assets less intangibles, to be used as a
supplement to risk-based guidelines. The principal objective of the leverage
ratio is to constrain the maximum degree to which a bank holding company may
leverage its equity capital base. The Federal Reserve requires a minimum
leverage ratio of 3%. However, for all but the most highly rated bank 



                                       54

<PAGE>   65


holding companies and for bank holding companies seeking to expand, the Federal
Reserve expects an additional cushion of at least 1% to 2%.

         FDICIA created a statutory framework of supervisory actions indexed to
the capital level of the individual institution. Under regulations adopted by
the FDIC, an institution is assigned to one of five capital categories depending
on its total risk-based capital ratio, Tier I risk-based capital ratio, and
leverage ratio, together with certain subjective factors. Institutions which are
deemed to be "undercapitalized" depending on the category to which they are
assigned are subject to certain mandatory supervisory corrective actions. USBN
and BFC do not believe that these regulations have any material effect on their
operations.

EFFECTS OF GOVERNMENT MONETARY POLICY

         The earnings and growth of USBN and BFC are affected not only by
general economic conditions, but also by the fiscal and monetary policies of the
federal government, particularly the Federal Reserve. The Federal Reserve can
and does implement national monetary policy for such purposes as curbing
inflation and combating recession, but its open market operations in U.S.
government securities, control of the discount rate applicable to borrowings
from the Federal Reserve, and establishment of reserve requirements against
certain deposits, influence the growth of bank loans, investments and deposits,
and also affect interest rates charged on loans or paid on deposits. The nature
and impact of future changes in monetary policies and their impact on USBN, BFC,
the Subsidiaries and the Bank cannot be predicted with certainty.

CHANGES IN BANKING LAWS AND REGULATIONS

         The laws and regulations that affect banks and bank holding companies
are currently undergoing significant changes. This year, legislation was
proposed in Congress which contained proposals to alter the structure,
regulation, and competitive relationships of the nation's financial
institutions. Although the legislation was not passed in the 1998 general
session of Congress, similar legislation may be proposed in the coming years
and, if enacted into law, such bills could have the effect of increasing or
decreasing the cost of doing business, limiting or expanding permissible
activities (including activities in the insurance and securities fields), or
affecting the competitive balance among banks, savings associations, and other
financial institutions. Some of these bills may reduce the extent of federal
deposit insurance, broaden the powers or the geographical range of operations of
bank holding companies, alter the extent to which banks could engage in
securities activities, and change the structure and jurisdiction of various
financial institution regulatory agencies. Whether or in what form such
legislation may be adopted, or the extent to which the business of USBN might be
affected thereby, cannot be predicted with certainty.

                        DESCRIPTION OF USBN CAPITAL STOCK

         USBN is authorized to issue 15,000,000 shares of common stock, no par
value per share. At November 10, 1998, the date the Merger Agreement was
executed, 4,546,722 shares of USBN common stock were issued and outstanding. A
total of 192,860 shares are subject to options under USBN stock option plans;
107,395 of such options are fully vested and exercisable. USBN common stock is
listed for trading on Nasdaq under the symbol "USBN." Each share of USBN common
stock has the same relative rights and is identical in all respects with every
other share of USBN common stock. The following summary describes the material
aspects of USBN common stock, but does not purport to be a complete description
of the applicable provisions of the USBN Articles of Incorporation and Bylaws or
of applicable statutory or other law, and is qualified in its entirety by
reference to those documents. See "WHERE YOU CAN FIND MORE INFORMATION."



                                       55

<PAGE>   66


VOTING RIGHTS

         The holders of USBN common stock possess exclusive voting rights in
USBN. Each holder of USBN common stock is entitled to one vote for each share
held of record on all matters submitted to a vote of holders of USBN common
stock. Holders of shares of USBN common stock are not entitled to cumulate votes
for the election of directors.

DIVIDENDS

         The holders of USBN common stock are entitled to such dividends as the
USBN board of directors may declare from time to time out of funds legally
available for payment of dividends. Dividends from USBN depend upon the receipt
to USBN of dividends from its subsidiary banks because USBN has no source of
income other than dividends from those banks. Accordingly, the dividend
restrictions imposed on USBN's subsidiary banks by statute or regulation may
effectively limit the amount of dividends USBN can pay. See "SUPERVISION AND
REGULATION -- Dividend Restrictions."

LIQUIDATION

         In the event of liquidation, dissolution or winding up of USBN, the
holders of shares of USBN common stock are entitled to share ratably in all
assets remaining after payment of all debts and other liabilities of USBN.

OTHER CHARACTERISTICS

         Holders of USBN common stock do not have any preemptive, conversion or
other subscription rights with respect to any additional shares of USBN common
stock which may be issued. Therefore, the USBN board of directors may authorize
the issuance and sale of shares of capital stock of USBN without first offering
them to existing stockholders of USBN. USBN common stock is not subject to any
redemption or sinking fund provisions. The outstanding shares of USBN common
stock are, and the shares to be issued in the Merger will be, fully paid and
non-assessable.

                     COMPARISON OF CERTAIN RIGHTS OF HOLDERS
                          OF USBN AND BFC COMMON STOCK

GENERAL

         USBN is incorporated under the laws of the State of Washington and,
accordingly, the rights of USBN's stockholders are governed by USBN's Articles
of Incorporation, Bylaws and Washington law. BFC is also incorporated under the
laws of the State of Washington, and, accordingly, the rights of BFC's
stockholders are governed by BFC's Articles of Incorporation, Bylaws and
Washington law.

         Upon consummation of the Merger, stockholders of BFC will become
stockholders of USBN, and as such, their rights will be governed by USBN's
Articles of Incorporation, Bylaws and Washington law. The following is a summary
of material differences between the Articles of Incorporation and Bylaws of USBN
and the Articles of Incorporation and Bylaws of BFC. This discussion is not
intended to be a complete statement of the differences affecting the rights of
stockholders and is qualified in its entirety by reference to the governing laws
and the Articles and Bylaws of each entity.

DIVIDEND RIGHTS

         USBN and BFC. Under Washington law, dividends may be paid only if,
after giving effect to the dividend, the corporation will be able to pay its
debts as they become due in the ordinary course of business and 



                                       56

<PAGE>   67


the corporation's total assets will not be less than the sum of its total
liabilities plus the amount that would be needed, if the corporation were to be
dissolved at the time of the dividend, to satisfy the preferential rights of
persons whose right to payment is superior to those receiving the dividend.

VOTING RIGHTS

         USBN. USBN's Articles of Incorporation eliminate cumulative voting.
Cumulative voting entitles each stockholder to cast a number of votes in the
election of directors equal to the number of such stockholders' shares of common
stock multiplied by the number of directors to be elected, and to distribute
such votes among one or more of the nominees to be elected. The absence of
cumulative voting rights limits the ability of minority stockholders to obtain
representation on the USBN board. All voting rights are vested in the holders of
USBN common stock, with each share being entitled to one vote.

         BFC. BFC's Articles of Incorporation also eliminate cumulative voting.
Each share of BFC common stock is entitled to one vote.

PREEMPTIVE RIGHTS

         USBN and BFC. Neither USBN's nor BFC's stockholders have preemptive
rights to subscribe to any additional securities that may be issued.

LIQUIDATION RIGHTS

         USBN and BFC. If either USBN or BFC is liquidated, its holders of
common stock are entitled to share, on a pro rata basis, the corporation's
remaining assets after payment of or provision for all debts and other
liabilities.

ASSESSMENTS

         USBN and BFC. All shares of USBN common stock and BFC common stock are
fully paid and nonassessable.

STOCK REPURCHASES

         USBN and BFC. Under Washington law, a corporation may acquire shares of
its own stock. Therefore, USBN and BFC may repurchase shares of their own
capital stock.

AMENDMENT OF ARTICLES AND BYLAWS

         USBN. USBN's Articles of Incorporation may be amended by the vote of
the holders of a majority of the outstanding shares of USBN common stock. The
Bylaws of USBN may be amended by a majority vote of the board of directors or by
the holders of at least a majority of the outstanding shares of USBN common
stock.

         BFC. BFC's Articles of Incorporation may be amended by the affirmative
vote of the holders of two-thirds of the outstanding BFC common stock. The
Bylaws of BFC may be amended, altered or repealed by a majority vote of the
board of directors of BFC or by the holders of a majority of the outstanding
shares of BFC.

APPROVAL OF CERTAIN TRANSACTIONS

         USBN. The Articles of Incorporation and Bylaws of USBN do not require
any increased stockholder vote to approve a business combination that may have
the effect of foreclosing reorganization, consolidations, 



                                       57

<PAGE>   68


sale of substantially all assets or dissolution which a majority of stockholders
deem desirable and place the power to prevent such a reorganization or
combination in the hands of a minority of stockholders.

         BFC. The Articles of Incorporation and Bylaws of BFC do not require any
increased stockholder vote above the two-thirds requirement of the WBCA to
approve a merger or consolidation.

DISSENTERS' RIGHTS

         USBN. Under the Washington Business Corporation Act ("WBCA"),
stockholders of USBN will generally have dissenter's appraisal rights in
connection with (i) a plan of merger to which USBN is a party; (ii) a plan of
share exchange to which USBN is a party as the corporation whose shares will be
acquired; (iii) certain sales or exchanges of all, or substantially all, of
USBN's property other than in the regular course of business; and (iv)
amendments to USBN's Articles of Incorporation effecting a material reverse
stock split. However, stockholders generally will not have such dissenters'
rights if stockholders approval is not required by the WBCA for the corporate
action. Approval of the Merger by the holders of USBN common stock is not
required under the WBCA; therefore stockholders of USBN do not have dissenters'
rights in connection with the Merger.

         BFC. Dissenters' rights applicable to BFC stockholders are the same as
those applicable to USBN stockholders. BFC stockholders are entitled to
dissenters' rights with respect to the Merger. See "THE MERGER -- Dissenters'
Rights of Appraisal."

BOARD OF DIRECTORS

         USBN. USBN's Articles of Incorporation provide that its board of
directors shall consist of not less than five nor more than 25 members, with the
current number set at eleven by a resolution of the board of directors of USBN.
The Articles of Incorporation of USBN provide that the board of directors or the
stockholders may change the authorized number of directors within the stated
range by resolution. Changes in the size of the range may be made by an
amendment to USBN's Articles of Incorporation, which must be approved by a
majority of the outstanding shares entitled to vote. The Bylaws of USBN provide
that any vacancy on the board of directors may be filled by the affirmative vote
of a majority of the remaining directors, and any director so appointed is to
serve for an unexpired term of his or her predecessor. The full board is elected
annually by the USBN stockholders.

         BFC. BFC's Articles of Incorporation provide that its board of
directors shall not consist of less than five and no more than twenty-five
members, with the current number set at six by resolution of the board of
directors of BFC. In the event of a vacancy on the board of directors, the
remaining board of directors may elect a director, by a majority vote, to fill
the vacancy for the balance of the term of his or her predecessor. BFC's
Articles of Incorporation or Bylaws do not provide for a procedure to remove a
director. Although BFC's Articles of Incorporation do not provide for a
classified or staggered board of directors, BFC stockholders have historically
elected directors on a classified basis. This matter is addressed at "DIRECTOR
CONFIRMATION."

INDEMNIFICATION AND LIMITATION OF LIABILITY

         USBN. Pursuant to USBN's Bylaws, USBN will indemnify the officers,
directors and employees of USBN with respect to expenses, settlements,
judgements and fines in suits in which such person has made a party by reason of
the fact that he or she is or was an officer, director or employee of USBN. No
such indemnification may be given if the acts or omissions of the person are
adjudged to be negligent or in bad faith. In addition, USBN's Bylaws provide
that neither a director or officer will be liable for negligence or bad faith in
the performance of his or her duties as director or officer if he or she acted
in good faith for a purpose which he or 



                                       58

<PAGE>   69


she reasonably believed to be in the best interests of the corporation of and
had no reasonable cause to believe that his or her conduct was unlawful.

         BFC. Pursuant to BFC's Articles on Incorporation and Bylaws, BFC may,
to the fullest extent permitted by the WBCA, indemnify directors, officers or
employees against expenses, fines, judgements and settlements incurred by such
person in connection with any action, suit or proceeding by reason of the fact
that such person is or was a director, officer or employee of BFC.
Indemnification may not be given in the event the liability of a director was
incurred by reason of intentional misconduct, a knowing violation of law,
unlawful distribution, or in connection with any transaction in which it is
finally adjudged that such director personally received a benefit in money,
property or services to which that director was not legally entitled. BFC's
Articles of Incorporation further provide that directors, to the fullest extent
permitted by the WBCA, shall not be liable to BFC or its stockholders for
monetary damages for conduct as a director except for acts or omissions finally
adjudged to be intentional misconduct, a knowing violation of law, unlawful
distribution or any transaction in which it is finally adjudged that such
director personally received a benefit in money, property or services to which
that director was not legally entitled.

POTENTIAL ANTI-TAKEOVER PROVISIONS

         Neither USBN's or BFC's Articles or Bylaws contain provisions that have
an anti-takeover effect on any proposed merger, consolidation, acquisition, or
similar transaction.

                              CERTAIN LEGAL MATTERS

         The validity of the USBN common stock to be issued in the Merger is
being passed upon for USBN by Graham & Dunn P.C., Seattle, Washington. Graham &
Dunn P.C. will also deliver an opinion concerning certain federal income tax
consequences of the Merger.

                                     EXPERTS

         The consolidated statement of financial condition of USBN as of
December 31, 1997 and the related consolidated statements of income,
stockholders' equity and cash flows for the year then ended, incorporated by
reference in USBN's Annual Report on Form 10-K for the year ended December 31,
1997 have been audited by Moss Adams LLP, independent auditors, as set forth in
their report thereon incorporated by reference therein and incorporated herein
by reference. Such consolidated statements are incorporated herein by reference
in reliance upon such report given upon the authority of such firm as experts in
accounting and auditing.

         The consolidated statements of financial condition of USBN as of
December 31, 1996 and December 31, 1995 and the related consolidated statements
of income, stockholders' equity and cash flows for the years then ended, (and
not presented separately or incorporated separately by reference herein), have
been audited by McFarland & Alton P.S., independent certified public
accountants, as stated in their report, which is incorporated by reference from
USBN's Annual Report on Form 10-K for the year ended December 31, 1997. Such
consolidated statements are incorporated herein by reference in reliance upon
such report given upon the authority of such firm as experts in accounting and
auditing.

         The financial statements of BFC as of and for the year ended December
31, 1997 included in this Prospectus/Joint Proxy Statement and in the
Registration Statement have been audited by Moss Adams, LLP, independent
auditors, to the extent and for the periods set forth in their report appearing
elsewhere herein, and are included in reliance upon such report given upon the
authority of said firm as experts in auditing and accounting.



                                       59

<PAGE>   70


                       WHERE YOU CAN FIND MORE INFORMATION

         USBN files annual, quarterly and current reports, proxy statements, and
other information with the SEC. You may read and copy any reports, statements,
or other information that USBN files at the SEC's public reference room at 450
Fifth Street, N.W., Washington, D.C. 20549. You can request copies of these
documents, upon payment of a duplicating fee, by writing the SEC. Please call
the SEC at 1-800-SEC-0330 for further information on the operation of the public
reference rooms. USBN's SEC filings are also available to the public on the SEC
Internet site (http://www.sec.gov).

         USBN has filed a Registration Statement on Form S-4 (File No. 333-
______) to register with the SEC, the USBN common stock to be issued to BFC
stockholders in the Merger. This Prospectus/Joint Proxy Statement is part of
that Registration Statement and constitutes a prospectus of USBN in addition to
being a proxy statement of USBN for the USBN special stockholders meeting and of
BFC for the BFC special stockholders meeting. As allowed by SEC rules, this
Prospectus/Joint Proxy Statement does not contain all of the information that
you can find in the Registration Statement or the exhibits to the Registration
Statement.

                      INFORMATION INCORPORATED BY REFERENCE

         The SEC allows USBN to "incorporate by reference" information into this
Prospectus/Joint Proxy Statement, which means that USBN can disclose important
information to you by referring you to another document filed separately by USBN
with the SEC. The information incorporated by reference is deemed to be part of
this Prospectus/Joint Proxy Statement, except for any information superseded by
any information in this Prospectus/Joint Proxy Statement. This Prospectus/Joint
Proxy Statement incorporates by reference the documents set forth below that
USBN has previously filed with the SEC. These documents contain important
information about USBN and its finances:

         -        Annual Report on Form 10-K for the year ended December 31,
                  1997;

         -        Quarterly Reports on Form 10-Q for the quarters ended March
                  31, 1998; June 30, 1998 and September 30, 1998;

         -        Proxy Statement for USBN's 1998 Annual Meeting of
                  Stockholders; and

         -        Current Reports on Form 8-K filed March 27, 1998; June 4,
                  1998; July 23, 1998; and November 13, 1998.

         USBN is also incorporating by reference additional documents that USBN
files with the SEC between the date of this Prospectus/Joint Proxy Statement and
the date of the special meeting of the USBN and BFC stockholders.

         You can obtain the documents that are incorporated by reference through
USBN or the SEC. You can obtain the documents from the SEC, as described above
under "WHERE YOU CAN FIND MORE INFORMATION." These documents are also available
from USBN without charge, excluding exhibits unless USBN has specifically
incorporated such exhibits by reference in this Prospectus/Joint Proxy
Statement. You may obtain documents incorporated by reference in this
Prospectus/Joint Proxy Statement by requesting them from USBN at 9506 North
Newport Highway, Spokane, Washington 99218-1200 ATTN: Jackie Barnard. USBN's
telephone number is (509) 467-6949. If you would like to request documents from
USBN, please do so by January ___, 1999 in the case of USBN stockholders, and
January ___, 1999 in the case of BFC stockholders, in order to receive them
before the USBN and BFC special stockholders meetings.



                                       60


<PAGE>   71


         USBN has supplied all of the information concerning it contained in
this Prospectus/Joint Proxy Statement, and BFC has supplied all of the
information concerning it.

         YOU SHOULD RELY ONLY ON THE INFORMATION CONTAINED OR INCORPORATED BY
REFERENCE IN THIS PROSPECTUS/JOINT PROXY STATEMENT IN DECIDING HOW TO VOTE ON
THE MERGER. WE HAVE NOT AUTHORIZED ANYONE TO PROVIDE YOU WITH INFORMATION OTHER
THAN WHAT IS CONTAINED IN THIS PROSPECTUS/JOINT PROXY STATEMENT. THIS
PROSPECTUS/JOINT PROXY STATEMENT IS DATED DECEMBER __, 1998. YOU SHOULD NOT
ASSUME THAT INFORMATION CONTAINED IN THIS PROSPECTUS/JOINT PROXY STATEMENT IS
ACCURATE AS OF ANY OTHER DATE, AND NEITHER THE MAILING OF THIS PROSPECTUS/JOINT
PROXY STATEMENT TO USBN OR BFC STOCKHOLDERS NOR THE ISSUANCE OF USBN COMMON
STOCK IN THE MERGER WILL CREATE ANY IMPLICATION TO THE CONTRARY.

                                  OTHER MATTERS

         Neither the USBN board of directors nor the BFC board of directors is
aware of any business to come before the USBN or BFC special stockholders
meetings, other than those matters described above in this Prospectus/Joint
Proxy Statement. However, if any other matters should properly come before such
meetings, it is intended that proxies in the accompanying forms will be voted on
such matters in accordance with the judgment of the person or persons voting the
proxies.



                                       61

<PAGE>   72
                          INDEPENDENT AUDITOR'S REPORT


To the Board of Directors and Stockholders
Bancwest Financial Corporation


We have audited the accompanying consolidated balance sheet of Bancwest
Financial Corporation and subsidiary (the Company) as of December 31, 1997, and
the related consolidated statements of income, changes in stockholders' equity,
and cash flows for the year then ended. These consolidated financial statements
are the responsibility of the Company's management. Our responsibility is to
express an opinion on these financial statements based on our audit.

We conducted our audit in accordance with generally accepted auditing standards.
Those standards require that we plan and perform the audit to obtain reasonable
assurance about whether the financial statements are free of material
misstatement. An audit includes examining, on a test basis, evidence supporting
the amounts and disclosures in the financial statements. An audit also includes
assessing the accounting principles used and significant estimates made by
management, as well as evaluating the overall financial statement presentation.
We believe that our audit provides a reasonable basis for our opinion.

In our opinion, the 1997 consolidated financial statements referred to above
present fairly, in all material respects, the financial position of Bancwest
Financial Corporation and subsidiary as of December 31, 1997, and the results of
their operations and their cash flows for the year then ended, in conformity
with generally accepted accounting principles.

                                                              /s/ MOSS ADAMS LLP

Everett, Washington
November 13, 1998


<PAGE>   73

                         BANCWEST FINANCIAL CORPORATION

                           CONSOLIDATED BALANCE SHEET
                                 (IN THOUSANDS)

<TABLE>
<CAPTION>
                                                                    DECEMBER 31,     
                                                            -------------------------      SEPTEMBER 30,
                                                              1997            1996            1998
                                                            ---------       ---------      -------------
                                                                  (Unaudited)              (Unaudited)
<S>                                                         <C>             <C>            <C>      
ASSETS
   Cash and due from banks                                  $   3,070       $   2,819       $   2,288
   Federal funds sold                                                             795             725
   Securities available-for-sale                               20,959          18,180          17,328
   Securities held-to-maturity                                  7,574           8,058           8,399
   Federal Home Loans Bank stock                                  848             786             897

   Loans                                                       67,272          60,255          71,210
   Less allowance for loan losses                              (1,004)           (611)           (865)
                                                            ---------       ---------       ---------

                                                               66,268          59,644          70,345
                                                            ---------       ---------       ---------

   Premises and equipment, net                                  2,207           1,972           2,184
   Accrued interest receivable                                  1,263           1,005           1,599
   Foreclosed real estate                                         200                              80
   Other assets                                                   120             253             239
                                                            ---------       ---------       ---------

         Total assets                                       $ 102,509       $  93,512       $ 104,084
                                                            =========       =========       =========

LIABILITIES
   Deposits
      Noninterest-bearing                                   $  18,381       $  15,467       $  17,107
      Interest-bearing                                         68,909          66,903          73,065

         Total deposits                                        87,290          82,370          90,172

   Federal funds purchased                                      4,295                             677
   Accrued interest payable                                       428             421             512
   Dividends payable                                                            2,798
   Other liabilities                                              785             428           1,002
                                                            ---------       ---------       ---------

         Total liabilities                                     92,798          86,017          92,363
                                                            ---------       ---------       ---------

STOCKHOLDERS' EQUITY
   Common stock, no par value; 1,000,000 shares
      authorized; 355,684 and 349,723 shares
      issued in 1997 and 1996, respectively                       356             350             364
   Additional paid-in capital                                   3,559           3,425           3,799
   Retained earnings                                            5,680           3,749           7,340
   Accumulated comprehensive income (loss), net of tax            116             (29)            218
                                                            ---------       ---------       ---------

         Total stockholders' equity                             9,711           7,495          11,721
                                                            ---------       ---------       ---------

         Total liabilities and stockholders' equity         $ 102,509       $  93,512       $ 104,084
                                                            =========       =========       =========
</TABLE>

   The accompanying notes are an integral part of these financial statements.



                                      F-2
<PAGE>   74

                         BANCWEST FINANCIAL CORPORATION

                        CONSOLIDATED STATEMENT OF INCOME
          (IN THOUSANDS EXCEPT NUMBER OF SHARES AND PER SHARE AMOUNTS)

<TABLE>
<CAPTION>
                                                                                          NINE MONTHS ENDED
                                                    YEAR ENDED DECEMBER 31,                  SEPTEMBER 30,
                                           --------------------------------------      -----------------------
                                             1997          1996           1995            1998          1997
                                           ---------     ---------      ---------      ---------     ---------
                                                        (Unaudited)    (Unaudited)    (Unaudited)   (Unaudited)
<S>                                        <C>          <C>            <C>            <C>           <C>      
INTEREST INCOME
   Interest and fees on loans              $   6,682     $   6,230      $   5,471      $   5,536     $   4,995
   Interest on federal funds sold                  8            23             --             11             7
   Interest on securities                      1,720         1,504          1,162          1,198         1,269
                                           ---------     ---------      ---------      ---------     ---------

         Total interest income                 8,410         7,757          6,633          6,745         6,271
                                           ---------     ---------      ---------      ---------     ---------

INTEREST EXPENSE
   Interest on deposits                        3,054         2,789          2,476          2,451         2,257
   Interest on federal funds purchased           224           135             95            203           190
                                           ---------     ---------      ---------      ---------     ---------

         Total interest expense                3,278         2,924          2,571          2,654         2,447
                                           ---------     ---------      ---------      ---------     ---------

         Net interest income                   5,132         4,833          4,062          4,091         3,824
                                           ---------     ---------      ---------      ---------     ---------

PROVISION FOR LOAN LOSSES                        303            --             62            100            57
                                           ---------     ---------      ---------      ---------     ---------

         Net interest income after
             provision for loan losses         4,829         4,833          4,000          3,991         3,767
                                           ---------     ---------      ---------      ---------     ---------

NONINTEREST INCOME
   Service charges                               598           688            622            455           433
   Securities gains (losses)                       5           (38)            (5)             7             3
   Other operating income                        272           130             35            277           164
                                           ---------     ---------      ---------      ---------     ---------

         Total noninterest income                875           780            652            739           600

NONINTEREST EXPENSE
   Salaries and employee benefits              1,918         1,808          1,672          1,549         1,417
   Occupancy                                     338           413            419            302           228
   Other operating expenses                      635           546            627            530           414
                                           ---------     ---------      ---------      ---------     ---------

         Total noninterest expense             2,891         2,767          2,718          2,381         2,059
                                           ---------     ---------      ---------      ---------     ---------

INCOME BEFORE INCOME TAX                       2,813         2,846          1,934          2,349         2,308

PROVISION FOR INCOME TAX                         882           883            515            690           648
                                           ---------     ---------      ---------      ---------     ---------

NET INCOME                                 $   1,931     $   1,963      $   1,419      $   1,659     $   1,660
                                           =========     =========      =========      =========     =========

NET INCOME PER SHARE
   Basic                                   $    5.46     $    5.61      $    4.18      $    4.57     $    4.69
   Diluted                                 $    5.33     $    5.48      $    4.07      $    4.50     $    4.59
   Weighted average shares
      outstanding                            353,974       349,423        339,572        363,280       353,616
   Weighted average diluted
      shares outstanding                     362,407       358,005        348,753        368,541       362,049
</TABLE>

   The accompanying notes are an integral part of these financial statements.



                                      F-3
<PAGE>   75

                         BANCWEST FINANCIAL CORPORATION

            CONSOLIDATED STATEMENT OF CHANGES IN STOCKHOLDERS' EQUITY
                     (in thousands except number of shares)

<TABLE>
<CAPTION>
                                                                                                   Accumulated     Total
                                         Common Stock        Additional                                Other       Stock-
                                    ---------------------     Paid-in    Comprehensive  Retained   Comprehensive  holders'
                                     Shares       Amount      Capital       Income      Earnings   Income (Loss)   Equity
                                    --------     --------    ----------  -------------  --------   -------------  --------
<S>                                 <C>          <C>         <C>         <C>            <C>        <C>            <C>
BALANCE,
   December 31, 1994
   (Unaudited)                       335,018     $    335     $  2,770                  $  3,571     $    (52)    $  6,624
Net income                                                                 $  1,419        1,419                     1,419
Other comprehensive
       income, net of tax of $48
   Unrealized gains
       on securities                                                             94                        94           94
                                                                           --------
Comprehensive income                                                       $  1,513
                                                                           ========
Transfer to additional paid-in
   capital                                                         395                      (395)                         
Common stock sold and
   exercised under stock
   option plans                        4,682            5           58                                                  63
                                    --------     --------     --------                  --------     --------     --------
BALANCE,
   December 31, 1995
   (Unaudited)                       339,700          340        3,223                     4,595           42        8,200
Net income                                                                 $  1,963        1,963                     1,963
Other comprehensive
       income, net of tax
       benefit of $(36)
   Unrealized losses
       on securities                                                            (71)                      (71)         (71)
                                                                           --------
Comprehensive income                                                       $  1,892                                       
                                                                           ========
Transfer to additional paid-in
   capital                                                          11                       (11)                         
Stock repurchase                      (1,380)          (1)         (44)                                                (45)
Cash dividend                                                                             (2,798)                   (2,798)
Common stock sold and
   exercised under stock
   option plans                       11,403           11          235                                                 246
                                    --------     --------     --------                  --------     --------     --------
BALANCE,
   December 31, 1996
   (Unaudited)                       349,723          350        3,425                     3,749          (29)       7,495
Net income                                                                 $  1,931        1,931                     1,931
Other comprehensive
       income, net of tax of $75
   Unrealized gains
       on securities                                                            145                       145          145
                                                                           --------

Comprehensive income                                                       $  2,076                                       
                                                                           ========
Common stock sold and
   exercised under stock
   option plans                        5,961            6          134                                                 140
                                    --------     --------     --------                  --------     --------     --------
BALANCE,
   December 31, 1997                 355,684     $    356     $  3,559                  $  5,680     $    116     $  9,711
                                    ========     ========     ========                  ========     ========     ========
</TABLE>

   The accompanying notes are an integral part of these financial statements.




                                      F-4
<PAGE>   76

                         BANCWEST FINANCIAL CORPORATION

                      CONSOLIDATED STATEMENT OF CASH FLOWS
                                 (in thousands)

<TABLE>
<CAPTION>
                                                                                                                NINE MONTHS ENDED
                                                                          YEAR ENDED DECEMBER 31,                 SEPTEMBER 30,
                                                                  ------------------------------------      ----------------------
                                                                    1997          1996          1995          1998          1997
                                                                  --------      --------      --------      --------      --------
                                                                              (Unaudited)    (Unaudited)   (Unaudited)   (Unaudited)
<S>                                                               <C>         <C>            <C>           <C>           <C>     
CASH FLOWS FROM OPERATING ACTIVITIES
    Net income                                                    $  1,931      $  1,963      $  1,419      $  1,659      $  1,660
    Adjustments to reconcile net income to net cash
           provided by operating activities
       Provisions for loan losses                                      303            --            62           100            57
       Depreciation                                                    159           152           167           123           118
       Deferred income tax                                              62           138            (7)          278           128
       Net accretion on securities                                      18            41            73            10            14
       (Gain) loss on sale of securities available-for-sale             (5)           38             5            (7)           (3)
       Stock dividends received                                        (62)          (58)          (45)          (49)          (45)
       Gain (loss) on disposal of assets                               (15)           (1)           15                          (3)
       Increase (decrease) in accrued interest receivable and
           other assets                                                125          (184)         (208)         (396)         (323)
       Increase (decrease) in accrued interest payable and
           other liabilities                                           364        (2,985)         (837)           84         1,080
       Proceeds from sale of mortgage loans held for sale            2,078            --            --            --            --
       Origination of mortgage loans held for sale                      --            --            --            --            --
                                                                  --------      --------      --------      --------      --------

           Net cash from operating activities                        4,958          (896)          644         1,802         2,683
                                                                  --------      --------      --------      --------      --------

CASH FLOWS FROM INVESTING ACTIVITIES
    Net (increase) decrease in federal funds sold                      795          (450)          450          (725)           --
    Securities available-for-sale
       Proceeds from maturities or principal payments                2,340         3,103         2,925         5,491         3,230
       Purchases                                                    (6,489)      (10,560)       (2,890)       (1,500)       (4,817)
       Sales                                                         1,254         3,600            --            --         1,250
    Securities held-to-maturity
       Proceeds from maturities or principal payments                  595           141           885           120           400
       Purchases                                                      (111)         (920)       (1,025)         (915)         (105)
    Net increase in loans                                           (9,295)       (6,577)       (7,789)       (4,389)       (8,563)
    Additions to bank premises and equipment                          (353)          (83)         (296)         (164)          (44)
                                                                  --------      --------      --------      --------      --------

           Net cash from investing activities                      (11,264)      (11,746)       (7,740)       (2,082)       (8,649)
                                                                  --------      --------      --------      --------      --------

CASH FLOWS FROM FINANCING ACTIVITIES
    Net increase in deposits                                         4,920         9,612         8,063         2,868         6,688
    Net increase in federal funds purchased                          4,295            --          (975)       (3,618)           --
    Cash dividends paid                                             (2,798)        2,798            --            --            --
    Proceeds from issuance of stock                                    140           246            63           248            95
                                                                  --------      --------      --------      --------      --------

           Net cash from financing activities                        6,557        12,656         7,151          (502)        6,783
                                                                  --------      --------      --------      --------      --------

NET INCREASE (DECREASE) IN CASH AND DUE
       FROM BANKS                                                      251            14            55          (782)          817

CASH AND DUE FROM BANKS, beginning of year                           2,819         2,805         2,750         3,070         2,819
                                                                  --------      --------      --------      --------      --------

CASH AND DUE FROM BANKS, end of year                              $  3,070      $  2,819      $  2,805      $  2,288      $  3,636
                                                                  ========      ========      ========      ========      ========

SUPPLEMENTAL DISCLOSURES OF CASH FLOW
       INFORMATION
    Cash payments for
       Interest                                                   $  3,271      $  2,924      $  2,489      $  2,368      $  2,301
                                                                  ========      ========      ========      ========      ========

       Income taxes                                               $    790      $    707      $    538      $    467      $    620
                                                                  ========      ========      ========      ========      ========

SUPPLEMENTAL DISCLOSURE OF NONCASH
       INVESTING ACTIVITIES
    Foreclosed real estate acquired in settlement of loans        $    200      $     --      $     --      $     --      $     80
                                                                  ========      ========      ========      ========      ========
</TABLE>

   The accompanying notes are an integral part of these financial statements.



                                      F-5
<PAGE>   77

                         BANCWEST FINANCIAL CORPORATION

                   NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

       FOR THE YEARS ENDED DECEMBER 31, 1997 (AUDITED), 1996 (UNAUDITED),
                              AND 1995 (UNAUDITED)

NOTE 1 - DESCRIPTION OF BUSINESS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES

        BASIS OF PRESENTATION - The consolidated financial statements include
the accounts of Bancwest Financial Corporation and its wholly-owned subsidiary,
Bank of the West (the Company). All significant intercompany transactions and
balances have been eliminated in consolidation.

        DESCRIPTION OF BUSINESS - The Company is a Washington State bank holding
company headquartered in Walla Walla, Washington. The Company was organized as a
holding company for its principal bank subsidiary, Bank of the West (the Bank).
The Company conducts its business primarily through the Bank which provides a
full range of commercial banking services to small and medium-sized farms,
businesses, professionals and other individuals through four banking offices
located in Walla Walla, Waitsburg and Dayton, Washington.

        UNAUDITED INFORMATION - The accompanying unaudited financial statements
as of December 31, 1996 and 1995, for the years ended December 31, 1996 and
1995, as of and for the nine-month period ended September 30, 1998 and 1997,
have been prepared on the same basis as the Company's audited financial
statements as of and for the year ended December 31, 1997. In the opinion of
management, all adjustments necessary for a fair presentation of the Company's
financial position, results of operations, and cash flows in the unaudited
financial statements have been included. The interim period unaudited financial
statements do not include all of the disclosures required by generally accepted
accounting principles for complete financial statements. The results of
operations and cash flows for the nine months ended September 30, 1998, are not
necessarily indicative of the results expected for the year ending December 31,
1998.

        USE OF ESTIMATES - The preparation of the consolidated financial
statements in conformity with generally accepted accounting principles requires
management to make estimates and assumptions. These assumptions and estimates
affect the reported amounts of assets and liabilities and disclosures of
contingent assets and liabilities at the date of the consolidated financial
statements. They also affect the reported amounts of revenues and expenses
during the reporting period. Actual results could differ from those estimates.

        CASH EQUIVALENTS - For purposes of reporting cash flows, cash and cash
equivalents, include cash on hand and amounts due from banks. Cash and cash
equivalents have an original maturity of three months or less.

        INVESTMENT SECURITIES - Investment securities are classified into one of
three categories: (1) held-to-maturity, (2) available-for-sale, or (3) trading.
Investment securities are categorized as held-to-maturity when the Company has
the intent and ability to hold those securities to maturity. Securities which
are held-to-maturity are stated at cost and adjusted for amortization of
premiums and accretion of discounts, which are recognized as adjustments to
interest income.

        Investment securities categorized as available-for-sale are generally
held for investment purposes (to maturity), although unanticipated future events
may result in the sale of some securities. Available-for-sale securities are
recorded at estimated fair value, with the net unrealized gain or loss included
in comprehensive income, net of the related tax effect. Realized gains or losses
on dispositions are based on the net proceeds and the adjusted carrying amount
of securities sold, using the specific identification method.

        Declines in the fair value of individual held-to-maturity and
available-for-sale securities below their cost that are other than temporary are
recognized by write-downs of the individual securities to their fair value. Such
write-downs would be included in earnings as realized losses.

        Premiums and discounts are recognized in interest income using the
interest method over the period to maturity. The Company had no trading
securities at December 31, 1997 and 1996.



                                      F-6
<PAGE>   78

                         BANCWEST FINANCIAL CORPORATION

                   NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

       FOR THE YEARS ENDED DECEMBER 31, 1997 (AUDITED), 1996 (UNAUDITED),
                              AND 1995 (UNAUDITED)


NOTE 1 - DESCRIPTION OF BUSINESS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES
(continued)

        FEDERAL HOME LOAN BANK STOCK - The Company's investment in Federal Home
Loan Bank (the FHLB) stock is carried at par value ($100 per share), which
reasonably approximates its fair value. As a member of the FHLB system, the
Company is required to maintain a minimum level of investment in FHLB stock
based on specified percentages of its outstanding FHLB advances. The Company may
request redemption at par value of any stock in excess of the amount the Company
is required to hold. Stock redemptions are at the discretion of the FHLB.

        LOANS HELD-FOR-SALE - Mortgage loans originated and designated as
held-for-sale are carried at the lower of cost or estimated fair value, as
determined by quoted market prices, in aggregate. Net unrealized losses are
recognized in a valuation allowance by charges to income. Gains or losses on the
sale of such loans are based on the specific identification method.

        LOANS - Loans that management has the intent and ability to hold for the
foreseeable future, or until maturity or pay-off, are reported at their
outstanding principal, adjusted for any charge-offs, the allowance for loan
losses, and any deferred fees or costs on originated loans and unamortized
premiums or discounts on purchased loans. Loan origination fees and certain
direct origination costs are capitalized and recognized as an adjustment of the
yield of the related loan.

        The accrual of interest on impaired loans is discontinued when, in
management's opinion, the borrower may be unable to meet payments as they become
due. When interest accrual is discontinued, all unpaid accrued interest is
reversed. Interest income is subsequently recognized only to the extent cash
payments are received. Interest income on restructured loans is recognized
pursuant to the terms of the new loan agreement. Interest income on other
impaired loans is monitored and based upon the terms of the underlying loan
agreement. However, the recorded net investment in impaired loans, including
accrued interest, is limited to the present value of the expected cash flows of
the impaired loan, or the observable fair market value of the loan, or the fair
market value of the loan's collateral.

        ALLOWANCE FOR LOAN LOSSES - The allowance for loan losses is increased
by charges to income and decreased by charge-offs (net of recoveries) and
established through a provision for credit losses charged to expense. Loans are
charged against the allowance for credit losses when management believes that
the collectibility of the principal is unlikely. The allowance is an amount that
management believes will be adequate to absorb losses inherent in existing
loans, commitments to extend credit and standby letters of credit based on
evaluations of collectibility and prior loss experience of loans, commitments to
extend credit and standby letters of credit. The evaluations take into
consideration such factors as changes in the nature and volume of the portfolio,
overall portfolio quality, loan concentrations, specific problem loans,
commitments, standby letters of credit and current economic conditions that may
affect the borrowers' ability to pay.

        A material estimate that is particularly susceptible to significant
change relates to the determination of the allowance for losses on loans and the
valuation of real estate acquired in connection with foreclosures or in
satisfaction of loans. In connection with the determination of the estimated
losses on loans and foreclosed assets, management obtains independent appraisals
for significant properties.

        The majority of the Company's loan portfolio consists of agricultural
and commercial loans and single-family residential loans secured by real estate
in South Eastern Washington. The ultimate collectibility of a substantial
portion of the Company's loan portfolio may be susceptible to changes in local
market or agricultural conditions.

        While management uses available information to recognize losses on
loans, further reductions in the carrying amounts of loans may be necessary
based on changes in local economic conditions. In addition, regulatory agencies,
as an integral part of their examination process, periodically review the
estimated losses on loans. Such agencies may require the Company to recognize
additional losses based on their judgments about information available to them
at the time of their examination.



                                      F-7
<PAGE>   79

                         BANCWEST FINANCIAL CORPORATION

                   NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

       FOR THE YEARS ENDED DECEMBER 31, 1997 (AUDITED), 1996 (UNAUDITED),
                              AND 1995 (UNAUDITED)


NOTE 1 - DESCRIPTION OF BUSINESS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES
(continued)

        PREMISES AND EQUIPMENT - Premises and equipment are stated at cost, less
accumulated depreciation. Leasehold improvements are amortized on a
straight-line basis over the lives of the respective leases. Depreciation is
computed on the straight-line method over the following estimated useful lives:

<TABLE>
<S>                                                      <C>
           Building and improvements                     15 - 40 years
           Furniture, fixtures and equipment              3 - 15 years
</TABLE>

        FORECLOSED REAL ESTATE - Real estate properties acquired through, or in
lieu of, loan foreclosure are to be sold and are initially recorded at fair
value at the date of foreclosure establishing a new cost basis. After
foreclosure, valuations are periodically performed by management and the real
estate is carried at the lower of carrying amount or fair value less cost to
sell. Revenue and expenses from operations and changes in the valuation
allowance were insignificant at December 31, 1997, 1996 and 1995.

        INCOME TAXES - The Company records its provision for income taxes using
the liability method. Deferred tax assets and liabilities are reflected at
currently enacted income tax rates applicable to the period in which the
deferred tax assets or liabilities are expected to be realized or settled. As
changes in tax laws or rates are enacted, deferred tax assets and liabilities
are adjusted through the provision for income taxes.

        RESTRICTED ASSETS - Federal Reserve Board Regulations require
maintenance of certain minimum reserve balances on deposit with the Federal
Reserve Bank. The amounts of such balances on deposit were approximately
$471,000 and $430,000 at December 31, 1997 and 1996, respectively.

        STOCK OPTION PLANS - The Company recognizes the financial effects of
stock options in accordance with Accounting Principles Board Opinion (APB) No.
25, "Accounting for Stock Issued to Employees" (APB 25). Stock options are
issued at a price that approximates the fair value of the Company's stock as of
the grant date. Under APB 25, options issued in this manner do not result in the
recognition of employee compensation in the Company's financial statements. Note
13 contains information about the fair value of stock options as required by
Statement of Financial Accounting Standards (SFAS) No. 123, "Stock Based
Compensation" (SFAS 123).

        FINANCIAL INSTRUMENTS - In the ordinary course of business, the Company
has entered into off-balance sheet financial instruments consisting of
commitments to extend credit, commitments under credit card arrangements,
commercial letters of credit and standby letters of credit. Such financial
instruments are recorded in the financial statements when they are funded, or
related fees are incurred or received.

        EARNINGS PER SHARE - In January 1, 1997, the Company adopted SFAS No.
128, "Earnings Per Share." This Statement supersedes APB No. 15 "Earnings Per
Share" and establishes standards for computing and presenting earnings per
share. All prior years presented have been restated to conform with the new
requirements.

        Basic earnings per share amounts are computed based on the weighted
average number of shares outstanding during the period after giving retroactive
effect to stock dividends and stock splits. Diluted earnings per share amounts
are computed by determining the number of additional shares that are deemed
outstanding due to stock options under the treasury stock method.

        ADVERTISING COSTS - The Company expenses advertising costs as they are
incurred and are not considered to be material.



                                      F-8
<PAGE>   80

                         BANCWEST FINANCIAL CORPORATION

                   NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

       FOR THE YEARS ENDED DECEMBER 31, 1997 (AUDITED), 1996 (UNAUDITED),
                              AND 1995 (UNAUDITED)


NOTE 1 - DESCRIPTION OF BUSINESS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES
(continued)

        IMPACT OF NEW ACCOUNTING ISSUES - In June 1997, the FASB issued SFAS No.
130 "Reporting Comprehensive Income" (SFAS No. 130), which requires an
enterprise report, by major components and as a single total, the change in its
net assets during the period from non-owner sources; and SFAS No. 131
"Disclosures about Segments of an Enterprise and Related Information" (SFAS No.
131), which establishes annual and interim reporting standards for an
enterprise's operating segments and related disclosures about its products,
services, geographic areas, and major customers. SFAS No. 130 is effective for
fiscal years beginning after December 15, 1997 and has been retroactively
applied to all periods presented. Adoption of this statement did not impact the
Company's consolidated financial position, results of operations, or cash flows
because the effects were limited to the form and content of its disclosures.
SFAS No. 131 is also effective for fiscal years beginning after December 15,
1997, but is not considered applicable.

        SFAS No. 133, "Accounting for Derivative Instruments and Hedging
Activities" (SFAS No. 133) issued June 1998, must be adopted by the Company as
of January 1, 2000. This Statement establishes accounting and reporting
standards for derivative financial instruments and for hedging activities. Upon
adoption of the Statement, all derivatives must be recognized at fair value as
either assets or liabilities in the statement of financial position. Changes in
the fair value of derivatives not designated as hedging instruments are to be
recognized currently in earnings, or are to be recognized as a component of
other comprehensive income, depending on the intended use of the derivatives and
the resulting designations. Upon adoption, retroactive application of this
statement to financial statements of prior periods is not permitted. The Company
is currently in the process of evaluating the impact of SFAS No. 133 on its
consolidated financial position and results of operations.


NOTE 2 - INVESTMENT SECURITIES

        Investment securities have been classified according to management's
intent. The carrying amount of securities and their approximate fair values are
as follows (dollars in thousands):

        DECEMBER 31, 1997

        SECURITIES AVAILABLE-FOR-SALE

<TABLE>
<CAPTION>
                                                                  Gross            Gross
                                                Amortized       Unrealized       Unrealized         Fair
                                                  Cost            Gains            Losses           Value
                                                 --------        --------         --------         --------
<S>                                             <C>             <C>              <C>               <C>     
        U.S. Treasury and U.S. Government
           corporations and agencies             $ 20,784        $    196         $    (21)        $ 20,959

        SECURITIES HELD-TO-MATURITY

        State and political subdivisions            7,285             163              (69)           7,379
        Mortgage-backed securities                    289               1               --              290
                                                 --------        --------         --------         --------
                                                    7,574             164              (69)           7,669

                                                 $ 28,358        $    360         $    (90)        $ 28,628
                                                 ========        ========         ========         ========
</TABLE>



                                      F-9
<PAGE>   81

                         BANCWEST FINANCIAL CORPORATION

                   NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

       FOR THE YEARS ENDED DECEMBER 31, 1997 (AUDITED), 1996 (UNAUDITED),
                              AND 1995 (UNAUDITED)


NOTE 2 - INVESTMENT SECURITIES (continued)

        DECEMBER 31, 1996 (UNAUDITED)

        SECURITIES AVAILABLE-FOR-SALE

<TABLE>
<CAPTION>
                                                   Gross                           Gross
                                                 Amortized      Unrealized       Unrealized          Fair
                                                   Cost           Gains            Losses           Value
                                                 --------        --------         --------         --------
<S>                                              <C>            <C>              <C>               <C>     
        U.S. Treasury and U.S. Government
           corporations and agencies             $ 18,225        $      7         $    (52)        $ 18,180

        SECURITIES HELD-TO-MATURITY

        State and political subdivisions            7,705              59               --            7,764
        Mortgage-backed securities                    353              --               (2)             355
                                                 --------        --------         --------         --------

                                                    8,058              59               (2)           8,119
                                                 --------        --------         --------         --------

                                                 $ 26,283        $     66         $    (54)        $ 26,299
                                                 ========        ========         ========         ========
</TABLE>


        The amortized cost and estimated market value of securities
available-for-sale and securities held-to-maturity, at December 31, 1997, by
contractual maturity, are shown below. Expected maturities may differ from
contractual maturities because borrowers may have the right to call or prepay
obligations with or without prepayment penalties.

<TABLE>
<CAPTION>
                                            Available-For-Sale              Held-to-Maturity
                                         ------------------------      ------------------------
                                                        Estimated                     Estimated
                                         Amortized        Fair         Amortized        Fair
                                           Cost           Value          Cost           Value
                                         ---------      ---------      ---------      ---------
<S>                                      <C>            <C>            <C>            <C>    
        Due in one year or less           $ 1,289        $ 1,290        $   360        $   360
        Due from one to five years          7,602          7,631          3,477          3,492
        Due from five to ten years         11,893         12,038          2,423          2,478
        Due after ten years                    --             --          1,314          1,339
                                          -------        -------        -------        -------

              Totals                      $20,784        $20,959        $ 7,574        $ 7,669
                                          =======        =======        =======        =======
</TABLE>

        Proceeds from sales of available-for-sale investment securities were
$1.3 million, $3.6 million and none in 1997, 1996 and 1995, respectively.

        Gross gains from the sales of available-for-sale investment securities
were $5 thousand, none and $11 thousand in 1997, 1996 and 1995, respectively.
The Company incurred gross losses of none, $38 thousand and $16 thousand in
1997, 1996 and 1995, respectively.

        Investments in municipal debt obligations represent purchases of
municipal bonds located in various counties and municipalities in Oregon,
Washington and Idaho. The debt obligations were all within the credit ratings
acceptable under the Company's investment policy.

        Investment securities with a book value of $3.6 million and $2.4 million
at 1997 and 1996, respectively, have been pledged to secure public deposits, as
required by law. The estimated fair value of these pledged securities is $3.6
million and $2.4 million at December 31, 1997 and 1996, respectively.



                                      F-10
<PAGE>   82

                         BANCWEST FINANCIAL CORPORATION

                   NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

       FOR THE YEARS ENDED DECEMBER 31, 1997 (AUDITED), 1996 (UNAUDITED),
                              AND 1995 (UNAUDITED)


NOTE 3 - LOANS

        The major classifications of loans at December 31 are summarized as
follows (dollars in thousands):

<TABLE>
<CAPTION>
                                                1997             1996
                                              --------         --------
                                                              (Unaudited)
<S>                                           <C>             <C>     
        Agricultural                          $ 19,543         $ 18,557
        Real estate
           Construction                            148               --
           Mortgage                             13,164           12,494
           Commercial                            5,913            5,543
        Commercial                              20,599           17,562
        Consumer and other                       7,905            6,099
                                              --------         --------

                                                67,272           60,255
        Less allowance for loan losses          (1,004)            (611)
                                              --------         --------

                                              $ 66,268         $ 59,644
                                              ========         ========
</TABLE>

        Contractual maturities of loans as of December 31, 1997 are as shown
below. Actual maturities may differ from contractual maturities because
individual borrowers may have the right to prepay loans with or without
prepayment penalties.

<TABLE>
<CAPTION>
                                  Within          1 - 5          After
                                  1 Year          Years         5 Years         Total
                                  -------        -------        -------        -------
<S>                               <C>            <C>            <C>            <C>    
        Agricultural              $15,382        $ 3,161        $    --        $18,543
        Real estate
           Construction               148             --             --            148
           Mortgage                   651         10,189          2,324         13,164
           Commercial               1,050          3,739          1,124          5,913
        Commercial                 12,944          6,819          1,832         21,595
        Consumer and other          2,751          3,258          1,900          7,909
                                  -------        -------        -------        -------

                                  $32,926        $27,166        $ 7,180        $67,272
                                  =======        =======        =======        =======
</TABLE>

<TABLE>
<CAPTION>
                                                    1 - 5          After
                                                    Years         5 Years
                                                   -------        -------
<S>                                                <C>            <C>    
        Loans maturing after one year with:
           Fixed rates                             $22,238        $ 6,078
           Variable rates                           37,854          1,102
                                                   -------        -------

                                                   $60,092        $ 7,180
                                                   =======        =======
</TABLE>

        At December 31, 1997 and 1996, the Company had loans amounting to $1.9
million and $99 thousand that were specifically classified as impaired with an
average balance of $851 and $88, respectively. At December 31, 1997 and 1996,
the allowance for credit losses related to these loans was approximately $483
thousand and $20 thousand, respectively. For the remaining $1.4 million and $79
thousand of impaired loans, no allocation of the allowance for possible credit
losses was considered necessary at December 31, 1997 and 1996. Interest
collected on these loans in cash and included in income was approximately $190
thousand and $10 thousand in 1997 and 1996, respectively. If interest on these
loans had been accrued, such income would have approximated $190 thousand and
$10 thousand in 1997 and 1996, respectively. At December 31, 1997 and 1996,
there were no commitments to lend additional funds to borrowers whose loans were
classified as impaired.



                                      F-11
<PAGE>   83

                         BANCWEST FINANCIAL CORPORATION

                   NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

       FOR THE YEARS ENDED DECEMBER 31, 1997 (AUDITED), 1996 (UNAUDITED),
                              AND 1995 (UNAUDITED)


NOTE 3 - LOANS (continued)

        The effects of troubled debt restructuring are not considered material
to the Company's financial position and results of operations.


NOTE 4 - ALLOWANCE FOR LOAN LOSSES

        Changes in the allowance for loan losses are summarized as follows
(dollars in thousands):

<TABLE>
<CAPTION>
                                           1997          1996          1995
                                          ------        ------        ------
                                                     (Unaudited)    (Unaudited)
<S>                                       <C>        <C>            <C>   
        Balance, beginning of year        $  611        $  560        $  568
        Provision for loan losses            303            --            62
        Additions from recoveries            214           176           128
        Loans charged-off                    124           125           198
                                          ------        ------        ------

        Balance, end of year              $1,004        $  611        $  560
                                          ======        ======        ======
</TABLE>

NOTE 5 - PREMISES AND EQUIPMENT

        Premises and equipment at December 31 consisted of the following
(dollars in thousands):

<TABLE>
<CAPTION>
                                               1997             1996
                                              -------         -------
                                                             (Unaudited)
<S>                                           <C>            <C>    
        Land                                  $   237         $   237
        Buildings                               2,277           2,000
        Furniture and equipment                 1,177           1,123
        Leasehold improvements                     19              19
                                              -------         -------

                                                3,710           3,379
        Less: accumulated depreciation         (1,503)         (1,407)
                                              -------         -------

                                              $ 2,207         $ 1,972
                                              =======         =======
</TABLE>

        Depreciation expense on premises and equipment totaled $159 thousand in
1997, $152 thousand in 1996, and $167 thousand in 1995.



                                      F-12
<PAGE>   84

                         BANCWEST FINANCIAL CORPORATION

                   NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

       FOR THE YEARS ENDED DECEMBER 31, 1997 (AUDITED), 1996 (UNAUDITED),
                              AND 1995 (UNAUDITED)


NOTE 6 - DEPOSITS

        Interest-bearing deposits at December 31 consisted of the following
(dollars in thousands):

<TABLE>
<CAPTION>
                                                       1997           1996
                                                     -------        -------
                                                                  (Unaudited)
<S>                                                  <C>          <C>    
        Demand accounts                              $ 7,055        $ 6,886
        Money market accounts                         13,017         14,654
        Savings accounts                               9,682          8,989
        Certificates of deposit over $100,000         16,167         16,983
        Other certificates of deposit                 22,988         19,391
                                                     -------        -------

                                                     $68,909        $66,903
                                                     =======        =======
</TABLE>

At December 31, 1997, the scheduled maturities of certificates of deposit are as
follows (dollars in thousands):

<TABLE>
<S>                                                              <C>    
         1998                                                    $33,085
         1999                                                      4,777
         2000                                                        502
         2001                                                        365
         2002                                                        426
                                                                 -------
                                                                 $39,155
                                                                 =======
</TABLE>

NOTE 7 - CREDIT ARRANGEMENTS

        The Company is a member of the Federal Home Loan Bank of Seattle. As a
member, the Company has a committed line of credit up to 5 percent of total
assets, which matures December 1998. Borrowings generally provide for interest
at the then current published rates. There were no borrowings outstanding at
December 31, 1997 and 1996.

        At December 31, 1997, committed line of credit agreements, totaling
approximately $9 million, were available to the Company from unaffiliated banks
with maturities that range from January to December 1998. Such lines generally
provide for interest at the then existing federal funds rate. There were no
borrowings outstanding under these credit arrangements at December 31, 1997 and
1996.


NOTE 8 - FEDERAL FUNDS PURCHASED

        Federal funds purchased generally mature within one to four days from
the transaction date and provide for interest at the then current published
rate.



                                      F-13
<PAGE>   85

                         BANCWEST FINANCIAL CORPORATION

                   NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

       FOR THE YEARS ENDED DECEMBER 31, 1997 (AUDITED), 1996 (UNAUDITED),
                              AND 1995 (UNAUDITED)


NOTE 9 - INCOME TAXES

        The components of the provision for federal income tax expense for the
years ended December 31, are as follows (dollars in thousands):

<TABLE>
<CAPTION>
                                   1997           1996            1995
                                  -----           -----           -----
                                               (Unaudited)     (Unaudited)
<S>                               <C>          <C>             <C>  
        Current                   $ 867           $ 745           $ 522
        Deferred                     15             138              (7)
                                  -----           -----           -----

                                  $ 882           $ 883           $ 515
                                  =====           =====           =====
</TABLE>

        A reconciliation of the effective income tax rate with the federal
statutory rate is as follows (dollars in thousands):

<TABLE>
<CAPTION>
                                             1997                   1996 (Unaudited)            1995 (Unaudited)
                                     -------------------          -------------------          -------------------
                                     Amount         Rate          Amount         Rate          Amount         Rate
                                     ------         ----          ------         ----          ------         ----
<S>                                  <C>            <C>           <C>            <C>           <C>            <C>
        Federal income tax at
           statutory rates           $ 956             34%        $ 968             34%        $ 658             34%
        Effect of tax-exempt
           interest income            (138)            -5%         (163)            -6%         (122)            -6%
        Other                           64              2%           78              3%          (21)             1%
                                     -----          -----         -----          -----         -----          -----

                                     $ 882             31%        $ 883             31%        $ 515             29%
                                     =====          =====         =====          =====         =====          =====
</TABLE>

        The following are the significant components of deferred tax assets and
liabilities at December 31 (dollars in thousands):

<TABLE>
<CAPTION>
                                                   1997            1996
                                                   -----          -----
                                                               (Unaudited)
<S>                                                <C>         <C>  
        Deferred tax assets
           Allowance for loan losses               $ 300          $ 161
           Other                                      --             15
                                                   -----          -----

                                                     300            176
                                                   -----          -----
        Deferred tax liabilities
           Accumulated depreciation                 (213)          (185)
           Other                                    (152)           (71)
                                                   -----          -----

                                                    (365)          (256)
                                                   -----          -----

        Net deferred tax liabilities               $ (65)         $ (80)
                                                   =====          =====
</TABLE>


        The Company believes, based on available information, all deferred
assets will be realized in the normal course of business, therefore, these
assets have not been reduced by a valuation allowance.



                                      F-14
<PAGE>   86

                         BANCWEST FINANCIAL CORPORATION

                   NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

       FOR THE YEARS ENDED DECEMBER 31, 1997 (AUDITED), 1996 (UNAUDITED),
                              AND 1995 (UNAUDITED)


NOTE 10 - STOCKHOLDERS' EQUITY AND REGULATORY CAPITAL

        The Company is subject to various regulatory capital requirements
administered by the federal banking agencies. Failure to meet minimum capital
requirements can initiate certain mandatory and, possibly, additional
discretionary actions by regulators that, if undertaken, could have a direct
material effect on the Company's financial statements. Under capital adequacy
guidelines and the regulatory framework for prompt corrective action, the
Company must meet specific capital guidelines that involve quantitative measures
of the Company's assets, liabilities and certain off-balance sheet items as
calculated under regulatory accounting practices. The Company's capital amounts
and classification are also subject to qualitative judgments by the regulators
about components, risk weightings and other factors.

        Quantitative measures established by regulation to ensure capital
adequacy require the Company to maintain minimum amounts and ratios (set forth
in the following table) of total and Tier I capital (as defined in the
regulations) to risk-weighted assets (as defined), and of Tier I capital (as
defined) to average assets (as defined). Management believes, as of December 31,
1997, that the Company meets all capital adequacy requirements to which it is
subject.

        As of the most recent notification from the Federal Deposit Insurance
Corporation, the Bank was categorized as well capitalized under the regulatory
framework for prompt corrective action. To be categorized as well capitalized,
the Company must maintain minimum total risk-based, Tier I risk-based, Tier I
leverage ratios as set forth in the table. There are no conditions or events
since that notification that management believes have changed the institution's
category.



                                      F-15
<PAGE>   87

                         BANCWEST FINANCIAL CORPORATION

                   NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

       FOR THE YEARS ENDED DECEMBER 31, 1997 (AUDITED), 1996 (UNAUDITED),
                              AND 1995 (UNAUDITED)


NOTE 10 - STOCKHOLDERS' EQUITY AND REGULATORY CAPITAL (continued)

        The Company's actual capital amounts and ratios are also presented in
the table (dollars in thousands):

<TABLE>
<CAPTION>
                                                                                                           To Be Well
                                                                                                        Capitalized Under
                                                                          For Capital                   Prompt Corrective
                                             Actual                    Adequacy Purposes                Action Provisions
                                    ------------------------        ------------------------        ------------------------
As of December 31, 1997:             Amount          Ratio           Amount          Ratio           Amount           Ratio
                                    --------        --------        --------        --------        --------        --------
<S>                                 <C>             <C>             <C>             <C>             <C>             <C>  
Total Capital
   (to Risk-Weighted Assets)
       Consolidated                 $ 10,585         12.6%         * $6,701           * 8.0%         * $8,376         * 10.0%
       Bank                         $ 10,577         12.6%         * $6,701           * 8.0%         * $8,376         * 10.0%

Tier I Capital
   (to Risk-Weighted Assets)
       Consolidated                 $  9,581         11.4%         * $6,701           * 4.0%         * $5,025          * 6.0%
       Bank                         $  9,573         11.4%         * $6,701           * 4.0%         * $5,025          * 6.0%

Tier I Capital
   (to average Assets)
       Consolidated                 $  9,581          9.8%         * $6,701           * 4.0%         * $4,914          * 5.0%
       Bank                         $  9,573          9.8%         * $6,701           * 4.0%         * $4,914          * 5.0%

As of December 31, 1996:

Total Capital
   (to Risk-Weighted Assets)
       Consolidated                 $ 10,968         13.6%         * $6,406           * 8.0%         * $8,008         * 10.0%
       Bank                         $ 10,959         13.6%         * $6,406           * 8.0%         * $8,008         * 10.0%

Tier I Capital
   (to Risk-Weighted Assets)
       Consolidated                 $ 10,308         12.9%         * $3,203           * 4.0%         * $4,805          * 6.0%
       Bank                         $ 10,299         12.9%         * $3,203           * 4.0%         * $4,805          * 6.0%

Tier I Capital
   (to average Assets)
       Consolidated                 $ 10,308         11.3%         * $3,646           * 4.0%         * $4,557          * 5.0%
       Bank                         $ 10,299         11.3%         * $3,646           * 4.0%         * $4,557          * 5.0%
</TABLE>

--------------
* is greater than or equal to

                                      F-16
<PAGE>   88

                         BANCWEST FINANCIAL CORPORATION

                   NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

       FOR THE YEARS ENDED DECEMBER 31, 1997 (AUDITED), 1996 (UNAUDITED),
                              AND 1995 (UNAUDITED)


NOTE 11 - COMMITMENTS AND CONTINGENT LIABILITIES

        FINANCIAL INSTRUMENTS - The Company is party to financial instruments
with off-balance sheet risk in the normal course of business to meet the
financing needs of its customers. These financial instruments include
commitments to extend credit and standby letters of credit. These instruments
involve, to varying degrees, elements of credit risk in excess of the amount
recognized in the balance sheets.

        The Company's exposure to credit loss, in the event of nonperformance by
the other party to the financial instruments for commitments to extend credit
and standby letters of credit, is represented by the contractual amount of those
instruments. The Company uses the same credit policies in making commitments and
conditional obligations as it does for on-balance sheet instruments. A summary
of commitments at December 31 follows (dollars in thousands):

<TABLE>
<CAPTION>
                                                                        (Unaudited)
<S>                                                   <C>               <C>    
        Commitments to extend credit                  $19,193            $17,514
        Standby letters of credit                         102                 47
                                                      -------            -------

                                                      $19,295            $17,561
                                                      =======            =======
</TABLE>

        Commitments to extend credit are agreements to lend to a customer as
long as there is no violation of any condition established in the contract.
Commitments generally have fixed expiration dates or other termination clauses
and may require payment of a fee. Since some commitments are expected to expire
without being drawn upon, the total commitment amounts do not necessarily
represent future cash requirements. The Company's experience has been that
approximately 60% of loan commitments are drawn upon by customers. While
approximately all of commercial letters of credit are utilized, a significant
portion of such utilization is on an immediate payment basis. The Company
evaluates each customer's credit worthiness on a case-by-case basis. The amount
of collateral obtained, if it is deemed necessary by the Company upon extension
of credit, is based on management's credit evaluation of the counterparty.
Collateral held varies but may include accounts receivable, inventory, property
and equipment, and income producing properties.

        Standby letters of credit are conditional commitments issued by the
Company to guarantee the performance of a customer to a third party. Those
guarantees are primarily issued to support public and private borrowing
arrangements. The credit risk involved in issuing letters of credit is
essentially the same as that involved in extending loan facilities to customers.
Collateral held various as specified above, and is required in instances where
the Company deemed necessary.



                                      F-17
<PAGE>   89

                         BANCWEST FINANCIAL CORPORATION

                   NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

       FOR THE YEARS ENDED DECEMBER 31, 1997 (AUDITED), 1996 (UNAUDITED),
                              AND 1995 (UNAUDITED)


NOTE 12 - RELATED PARTY TRANSACTIONS

        Certain directors, executive officers, principal stockholders and
companies in which they have a beneficial interest, are loan customers of the
Company. All loans and loan commitments were made in compliance with applicable
laws and regulations on substantially the same terms (including interest rates
and collateral) as those prevailing at the time for comparable transactions with
other persons and do not involve more than the normal risk of collectibility or
present any other unfavorable features.

        Such loans had aggregate balances and activity during 1997, 1996 and
1995 as follows (dollars in thousands):

<TABLE>
<CAPTION>
                                             1997           1996           1995
                                            ------         ------         ------
                                                        (Unaudited)     (Unaudited)
<S>                                         <C>         <C>             <C>   
Balance at beginning of year                $1,318         $1,111         $   32
New loans or advances                        4,150          1,668          1,569
Repayments                                   2,259          1,461            490
                                            ------         ------         ------

Balance at end of year                      $3,209         $1,318         $1,111
                                            ======         ======         ======
</TABLE>

        Deposits from related parties totaled approximately $380 and $375 at
December 31, 1997 and 1996, respectively.


NOTE 13 - STOCK OPTION PLANS

        The Company has qualified incentive stock option plans that provide for
the awarding of stock options to certain officers, employees and directors of
the Company. The awarding of stock options is at the discretion of the Board of
Directors. Options granted under the plans vest under a schedule determined by
the Board of Directors and expire ten years from the date of the grant. The
exercise price of all options granted under the plan is equal to the fair value
of the common stock on the date of the grant. Average exercise price per share,
number of shares authorized, available for grant, granted, exercised,
outstanding and currently exercisable indicate the dilutive effect of stock
dividends and stock splits.

        Proforma information regarding net income and earnings per share is
required by SFAS No. 123, "Accounting for Stock-Based Compensation." The
proforma recognizes, as compensation, the estimated present value of stock
options granted using an option valuation model known as the Black-Scholes
model. Proforma earnings per share amounts reflect an adjustment as if the
present value of the options were recognized as compensation for the period.

        For the most part, variables and assumptions are used in the model. For
the periods 1997, 1996 and 1995, respectively, the risk-free interest rate is
5.4%, 5.6% and 5.6%, the dividend yield rate is 0.00% as the Company generally
pays no cash dividends, and the weighted average expected life of the options
has been measured at 5 years.

        Management believes that the variables and assumptions used in the
options pricing model are subjective and represent only one estimate of possible
value. The fair value of options granted that are recognized in proforma
earnings is shown below in thousands, except per share amounts:



                                      F-18
<PAGE>   90

                         BANCWEST FINANCIAL CORPORATION

                   NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

       FOR THE YEARS ENDED DECEMBER 31, 1997 (AUDITED), 1996 (UNAUDITED),
                              AND 1995 (UNAUDITED)


NOTE 13 - STOCK OPTION PLAN (continued)

<TABLE>
<CAPTION>
                                                   1997             1996              1995
                                                 ---------        ---------        ---------
                                                                 (Unaudited)      (Unaudited)
<S>                                              <C>             <C>              <C>      
Proforma disclosures
   Net income as reported                        $   1,931        $   1,963        $   1,419
   Additional compensation for fair value
       of stock options                                302              176              300
                                                 ---------        ---------        ---------

   Proforma net income                           $   1,629        $   1,787        $   1,119
                                                 =========        =========        =========
Earnings per share
   Basic
       As reported                               $    5.46        $    5.61        $    4.18
                                                 =========        =========        =========
       Proforma                                  $    4.60        $    5.11        $    3.30
                                                 =========        =========        =========
   Diluted
       As reported                               $    5.33        $    5.48        $    4.07
                                                 =========        =========        =========
       Proforma                                  $    4.49        $    4.99        $    3.21
                                                 =========        =========        =========
</TABLE>

        Information with respect to options granted under the stock option plans
is summarized as follows:

<TABLE>
<CAPTION>
                                                          Weighted
                                          Available       Average
                                         for Option/      Exercise       Options
                                           Award           Price       Outstanding      Exercisable
                                         -----------     ----------    -----------      -----------
<S>                                      <C>             <C>           <C>              <C>   
Balance, December 31, 1994                 20,868         $ 19.11         24,543          10,560

   Options granted                         (9,380)          26.28          9,380           5,860
   Options exercised                           --            8.87         (3,443)             --
                                          -------         -------        -------         -------

Balance, December 31, 1995                 11,488           22.47         30,480          16,420

   Options granted                         (4,628)          32.25          4,628           3,400
   Options exercised                           --           21.12         (9,727)         (6,880)
   Options expired and forfeitures            887           27.89           (887)             --
                                          -------         -------        -------         -------

Balance, December 31, 1996                  7,747           24.66         24,494          12,940

   Options authorized                      53,288              --             --              --
   Options granted                         (6,860)          40.63          6,860           3,260
   Options exercised                           --           17.31         (4,171)         (1,920)
   Options expired and forfeitures            879           27.73           (879)             --
                                          -------         -------        -------         -------

Balance, December 31, 1997                 55,054         $ 29.89         26,304          14,280
                                          =======         =======        =======         =======
</TABLE>



                                      F-19
<PAGE>   91

                         BANCWEST FINANCIAL CORPORATION

                   NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

       FOR THE YEARS ENDED DECEMBER 31, 1997 (AUDITED), 1996 (UNAUDITED),
                              AND 1995 (UNAUDITED)


NOTE 13 - STOCK OPTION PLAN (continued)

        Additional financial data pertaining to stock options outstanding as of
December 31, 1997 is as follows:

<TABLE>
<CAPTION>
                                          Weighted Average                                            Weighted Average
                                             Remaining        Weighted Average        Number          Exercise Price of
  Range of               Number of           Contractual     Exercise Price of      Exercisable         Exercisable
Exercise Prices        Option Shares       Life (In Years)     Option Shares       Option Shares       Option Shares
---------------        --------------     ----------------   -----------------     -------------      ------------------
<S>                    <C>                <C>                <C>                   <C>                <C>
$22.00 - $28.00              14,936                1.14          $    24.48               8,740          $    24.63

$28.01 - $34.00               4,149                2.76          $    31.18               2,280          $    32.00

$34.01 - $40.00               3,619                3.90          $    37.72               3,260          $    38.00

$40.01 - $46.20               3,600                4.00          $    43.01                  --                  --
</TABLE>

NOTE 14 - EARNINGS PER SHARE

        The numerators and denominators of basic and fully diluted earnings per
share are as follows:

In thousands, except for per share amounts

<TABLE>
<CAPTION>
                                                              1997            1996            1995
                                                            --------        --------        --------
                                                                           (Unaudited)     (Unaudited)
<S>                                                         <C>            <C>             <C>     
        Net income (numerator)                              $  1,931        $  1,963        $  1,419
                                                            ========        ========        ========

        Shares used in the calculation (denominator)
           Weighted average shares outstanding               353,974         349,423         339,572
           Effect of dilutive stock options                    8,433           8,582           9,181
                                                            --------        --------        --------

           Fully diluted shares                              362,407         358,005         348,753
                                                            ========        ========        ========

           Basic earnings per share                         $   5.46        $   5.61        $   4.18
                                                            ========        ========        ========

           Fully diluted earnings per share                 $   5.33        $   5.48        $   4.07
                                                            ========        ========        ========
</TABLE>



                                      F-20
<PAGE>   92

                         BANCWEST FINANCIAL CORPORATION

                   NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

       FOR THE YEARS ENDED DECEMBER 31, 1997 (AUDITED), 1996 (UNAUDITED),
                              AND 1995 (UNAUDITED)


NOTE 15 - FAIR VALUE OF FINANCIAL INSTRUMENTS

        The following disclosure of the estimated fair value of financial
instruments is made in accordance with the requirements of SFAS No. 107,
"Disclosures About Fair Value of Financial Instruments." The estimated fair
value amounts have been determined by the Company using available market
information and appropriate valuation methodologies. However, considerable
judgment is necessary to interpret market data in the development of the
estimates of fair value. Accordingly, the estimates presented herein are not
necessarily indicative of the amounts the Company could realize in a current
market exchange. The use of different market assumptions and/or estimation
methodologies may have a material effect on the estimated fair value amounts.
The following methods and assumptions were used to estimate the fair value of
each class of financial instruments for which it is practicable to estimate that
value:

        (a) CASH AND DUE FROM BANKS AND FEDERAL FUNDS SOLD AND PURCHASED - For
these short-term instruments, the carrying amount is a reasonable estimate of
fair value.

        (b) SECURITIES - Fair values for securities are based on quoted market
prices or dealer quotes, if available. If a quoted market price is not
available, fair value is estimated using quoted market prices for similar
securities. The fair values of restricted equity securities approximate fair
values.

        (c) LOANS - The fair value of loans generally is estimated by
discounting the future cash flows using the current rates at which similar loans
would be made to borrowers with similar credit ratings and for the same
remaining maturities. For certain homogeneous categories of loans, such as Small
Business Administration guaranteed loans, fair value is estimated using the
quoted market prices for securities backed by similar loans, adjusted for
differences in loan characteristics. Variable rate loans are assumed to equal
their carrying amount.

        (d) DEPOSITS - The fair value of demand deposits, savings accounts, and
certain money market deposits, is the amount payable on demand at the reporting
date. The fair value of fixed-maturity certificates of deposit is estimated by
discounting the future cash flows using the rates currently offered for deposits
of similar remaining maturities.

        (e) OFF-BALANCE SHEET FINANCIAL INSTRUMENTS - Commitments to extend
credit and letters of credit represent the principal categories of off-balance
sheet financial instruments. The fair value of these are not material since they
are generally for a short period of time and subject to customary credit terms.

        The estimated fair values of the Company's financial instruments at
December 31, are as follows (dollars in thousands):

<TABLE>
<CAPTION>
                                                                   1997                    1996 (Unaudited)
                                                         -----------------------        ----------------------
                                                         Carrying         Fair          Carrying        Fair
                                                          Amount          Value          Amount         Value
                                                         --------        -------        --------       -------
<S>                                                      <C>             <C>            <C>            <C>    
        Financial Assets:
           Cash and due from banks
               and Federal funds sold                     $ 3,070        $ 3,070        $ 3,614        $ 3,614
           Securities                                     $29,381        $29,476        $27,024        $27,081
           Loans, net of allowance for loan losses        $66,268        $67,006        $59,644        $60,292
        Financial Liabilities:
           Deposits                                       $87,290        $87,290        $82,370        $82,370
           Federal funds purchased                        $ 4,295        $ 4,295
</TABLE>



                                      F-21
<PAGE>   93

NOTE 16 - PARENT COMPANY (ONLY) FINANCIAL INFORMATION

        Condensed balance sheet at December 31 (dollars in thousands):

<TABLE>
<CAPTION>
                                                               1997              1996
                                                              -------          -------
                                                                              (Unaudited)
<S>                                                           <C>             <C>    
ASSETS
   Cash and due from bank                                     $    14          $     4
   Investment in Bank                                           9,689           10,280
   Other assets                                                     8                9
                                                              -------          -------

          Total assets                                        $ 9,711          $10,293
                                                              =======          =======

DIVIDENDS PAYABLE                                             $    --          $ 2,798

 STOCKHOLDERS' EQUITY                                           9,711            7,495
                                                              -------          -------

          Total liabilities and stockholders' equity          $ 9,711          $10,293
                                                              =======          =======
</TABLE>

     Condensed statement of income for the year ended December 31 (dollars in
thousands):

<TABLE>
<CAPTION>
                                                            1997             1996              1995
                                                          -------           -------          -------
                                                                          (Unaudited)      (Unaudited)
<S>                                                       <C>             <C>              <C>    
INCOME
   Dividend from Bank                                     $ 2,813           $    47          $    --
                                                          -------           -------          -------

          Total income                                      2,813                47               --
                                                          -------           -------          -------

EXPENSES
   Other expenses                                               6                 5                1
                                                          -------           -------          -------

NET INCOME BEFORE EQUITY IN UNDISTRIBUTED
   INCOME (DISTRIBUTIONS IN EXCESS OF INCOME) OF
   BANK                                                     2,807                42               (1)

EQUITY IN UNDISTRIBUTED INCOME (DISTRIBUTIONS IN
   EXCESS OF INCOME) OF BANK                                 (876)            1,921            1,420
                                                          -------           -------          -------

NET INCOME                                                $ 1,931           $ 1,963          $ 1,419
                                                          =======           =======          =======
</TABLE>



                                      F-22
<PAGE>   94

                         BANCWEST FINANCIAL CORPORATION

                   NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

       FOR THE YEARS ENDED DECEMBER 31, 1997 (AUDITED), 1996 (UNAUDITED),
                              AND 1995 (UNAUDITED)


NOTE 16 - PARENT COMPANY (ONLY) FINANCIAL INFORMATION (continued)

Condensed statement of cash flows for the year ended December 31 (dollars in
thousands):

<TABLE>
<CAPTION>
                                                                         1997              1996              1995
                                                                        -------           -------           -------
                                                                                        (Unaudited)       (Unaudited)
<S>                                                                     <C>             <C>               <C>    
CASH FLOWS FROM OPERATING ACTIVITIES
   Net income                                                           $ 1,931           $ 1,963           $ 1,419
   Adjustments to reconcile net income to net cash from
          operating activities
       Equity in undistributed income (distributions in excess
          of income) of Bank                                                876            (1,921)           (1,420)
       Other                                                                  1                (1)                1
                                                                        -------           -------           -------

          Net cash from operating activities                              2,808                41                --
                                                                                          -------           -------

CASH FLOWS FROM INVESTING ACTIVITIES
   Invest in subsidiary                                                    (140)             (246)              (63)
                                                                        -------           -------           -------

          Net cash from investing activities                               (140)             (246)              (63)
                                                                        -------           -------           -------

CASH FLOWS FROM FINANCING ACTIVITIES
   Issuance of common stock                                                 140               246                63
   Repurchase of common stock                                                --               (45)               --
   Cash dividends paid                                                   (2,798)               --                --
                                                                        -------           -------           -------

          Net cash from financing activities                             (2,658)              201                63
                                                                        -------           -------           -------

NET INCREASE IN CASH                                                         10                (4)               --

CASH, beginning of year                                                       4                 8                 8
                                                                        -------           -------           -------

CASH, end of year                                                       $    14           $     4           $     8
                                                                        =======           =======           =======
</TABLE>

NOTE 17 - PENDING ACQUISITIONS

        On November 12, 1998, the Company entered into an agreement and plan of
merger with United Security Bancorporation, pursuant to which the Company will
be merged into United Security Bancorporation. The merger agreement provides
that the Company's common stock be exchanged for shares of United Security
Bancorporation common stock pursuant to a specified exchange ratio. Consummation
of the acquisition is subject to several conditions, including receipt of
applicable regulatory and stockholder approval.


NOTE 18 - YEAR 2000

        The Company has developed a plan and has performed an evaluation of the
potential effect on its computer systems resulting from the Year 2000 issues.
Potential Year 2000 issues relate not only to the Company's systems, but also to
those of its customers and suppliers, and the Company has implemented a program
to monitor the Year 2000 efforts on its customers and suppliers, as well as an
internal evaluation of its computer information systems. Management has
identified the systems which will require program modifications or new software
installations in order to be Year 2000 compliant. The Company estimates it will
incur testing and remediation costs of approximately $200,000, which will be
funded through current cash flows from operations. The Company has incurred and
expensed approximately $60,000 related to this problem.




                                      F-23
<PAGE>   95

                                                                      APPENDIX A





                 ----------------------------------------------



                          AGREEMENT AND PLAN OF MERGER

                                     BETWEEN

                         UNITED SECURITY BANCORPORATION

                                       AND

                         BANCWEST FINANCIAL CORPORATION
                                       AND
                                BANK OF THE WEST



                 ----------------------------------------------





                          DATED AS OF NOVEMBER 10, 1998




<PAGE>   96



                                TABLE OF CONTENTS


<TABLE>
<S>                                                                                         <C>
I.  MERGER...................................................................................6

        1.1    THE MERGER....................................................................6
        1.2    DISSENTING SHARES.............................................................7
        1.3    EFFECTIVE DATE................................................................7

II.  CONSIDERATION...........................................................................7

        2.1    EXCHANGE CONSIDERATION........................................................7
        2.2    SHAREHOLDER RIGHTS; STOCK TRANSFERS...........................................8
        2.3    FRACTIONAL SHARES.............................................................8
        2.4    EXCHANGE PROCEDURES...........................................................8
        2.5    EXCHANGE RATIO ADJUSTMENT.....................................................8
        2.6    EXCEPTION SHARES..............................................................8
        2.7    RESERVATION OF RIGHT TO REVISE TRANSACTION....................................8
        2.8    OPTIONS.......................................................................9

III.  ACTIONS PENDING CONSUMMATION...........................................................9

        3.1    CAPITAL STOCK.................................................................9
        3.2    DIVIDENDS, ETC................................................................9
        3.3    INDEBTEDNESS; LIABILITIES; ETC................................................9
        3.4    LINE OF BUSINESS; OPERATING PROCEDURES; ETC..................................10
        3.5    LIENS AND ENCUMBRANCES.......................................................10
        3.6    COMPENSATION; EMPLOYMENT AGREEMENTS; ETC.....................................10
        3.7    BENEFIT PLANS................................................................10
        3.8    CONTINUANCE OF BUSINESS......................................................10
        3.9    AMENDMENTS...................................................................10
        3.10   CLAIMS.......................................................................10
        3.11   CONTRACTS....................................................................10
        3.12   LOANS........................................................................10
        3.13   TRANSACTION EXPENSES.........................................................11

IV.  REPRESENTATIONS AND WARRANTIES.........................................................11

        4.1    BANCWEST AND BANK OF THE WEST REPRESENTATIONS AND WARRANTIES.................11
        4.2    USBN REPRESENTATIONS AND WARRANTIES..........................................19

V.  COVENANTS...............................................................................21

        5.1    BEST EFFORTS.................................................................22
        5.2    THE PROXY....................................................................22
        5.3    REGISTRATION STATEMENT COMPLIANCE WITH SECURITIES LAWS.......................22
        5.4    REGISTRATION STATEMENT EFFECTIVENESS.........................................22
        5.5    PRESS RELEASES...............................................................22
        5.6    ACCESS; INFORMATION..........................................................23
</TABLE>



                                     A - i

<PAGE>   97


<TABLE>
<S>                                                                                         <C>
        5.7    REGISTRATION STATEMENT PREPARATION; REGULATORY APPLICATIONS PREPARATION......23
        5.8    BLUE-SKY FILINGS.............................................................23
        5.9    AFFILIATE AGREEMENTS.........................................................23
        5.10   CERTAIN POLICIES OF BANCWEST AND BANK OF THE WEST............................23
        5.11   STATE TAKEOVER LAW...........................................................23
        5.12   NO RIGHTS TRIGGERED..........................................................24
        5.13   SHARES LISTED................................................................24
        5.14   REGULATORY APPLICATIONS......................................................24
        5.15   REGULATORY DIVESTITURES......................................................24
        5.16   CURRENT INFORMATION..........................................................24
        5.17   INDEMNIFICATION..............................................................25
        5.18   BOARDS OF DIRECTORS OF USBN AND BANK OF THE WEST.............................25
        5.20   POST-MERGER ACTIONS..........................................................26

VI.  CONDITIONS TO CONSUMMATION OF THE MERGER...............................................26

        6.1    CONDITIONS TO EACH PARTY'S OBLIGATIONS.......................................26
        6.2    CONDITIONS TO OBLIGATIONS OF USBN............................................27
        6.3    CONDITIONS TO OBLIGATIONS OF BANCWEST AND BANK OF THE WEST...................28

VII.  TERMINATION...........................................................................29

        7.1    EVENTS OF TERMINATION........................................................29
        7.2    CONSEQUENCES OF TERMINATION..................................................30
        7.3    TERMINATION FEE..............................................................30

VIII.  OTHER MATTERS........................................................................30

        8.1    SURVIVAL.....................................................................30
        8.2    WAIVER; AMENDMENT............................................................31
        8.3    COUNTERPARTS.................................................................31
        8.4    GOVERNING LAW................................................................31
        8.5    EXPENSES.....................................................................31
        8.6    CONFIDENTIALITY..............................................................31
        8.7    NOTICES......................................................................31
        8.8    ENTIRE UNDERSTANDING; NO THIRD PARTY BENEFICIARIES...........................32
        8.9    BENEFIT PLANS................................................................32
        8.10   HEADINGS.....................................................................32
</TABLE>



                                     A - ii


<PAGE>   98




                                    EXHIBITS

<TABLE>
<S>            <C>
Exhibit A      Voting Agreement

Exhibit B      Director's Agreement

Exhibit C      Stock Option Agreement

Exhibit D      Employment Agreement

Exhibit E      Affiliate Agreement

Exhibit F      Legal Opinion of Keller Rohrback L.L.P.

Exhibit G      Legal Opinion of Graham & Dunn, P.C.
</TABLE>



                                    SCHEDULES

<TABLE>
<CAPTION>
Company Disclosures
-------------------
<S>                      <C>
Schedule 2.8             Outstanding Options

Schedule 3.4             Changes to Line of Business, Operating Procedures,
                         etc.

Schedule 3.6             New or Changes to Compensation, Employment
                         Agreements, etc.

Schedule 3.7             New or Modifications to Benefit Plans

Schedule 3.11            New or Changes to Material Contracts

Schedule 4.1(C)          Shares Outstanding

Schedule 4.1(D)          Subsidiaries

Schedule 4.1(G)          No Defaults -- Agreements Requiring Third Party
                         Consent

Schedule 4.1(H)          Financial Reports

Schedule 4.1(I)          Undisclosed Liabilities

Schedule 4.1(J)          No Events Causing Material Adverse Effect

Schedule 4.1(L)          Litigation, Regulatory Action

Schedule 4.1(M)          Compliance with Laws

Schedule 4.1(N)          Material Contracts
</TABLE>



                                    A - iii


<PAGE>   99


<TABLE>
<CAPTION>
Company Disclosures
-------------------
<S>                                         <C>
Schedule 4.1(P)          Brokers

Schedule 4.1(Q)(1)       List of Employee Benefit Plans

Schedule 4.1(Q)(2)       Employee Benefit Plans Not Qualified Under ERISA

Schedule 4.1(Q)(6)       Obligations for Retiree Health and Life Benefits

Schedule 4.1(Q)(7)       Agreements  Resulting in Payments to Employees  Under
                         Any  Compensation  and Benefit  Plan with  Respect to
                         Proposed Transaction

Schedule 4.1(T)          Asset Classification

Schedule 4.1(V)          Insurance

Schedule 4.1(W)          Affiliates

Schedule 4.1(Z)(2)       Pending  Proceedings  with  Respect to  Environmental
                         Matters

Schedule 4.1(Z)(3)       Pending  Proceedings  with  Respect to  Environmental
                         Matters Involving Loan/Fiduciary Property

Schedule 4.1(Z)(4)       Pending  Proceedings  with  Respect to  Environmental
                         Matters Listed in Sections 4.1(Z)(2) or (3)

Schedule 4.1(Z)(5)       Actions  During  Ownership  Which could Have Material
                         Adverse Effect with Respect to Environmental Matters

Schedule 4.1(Z)(6)       Actions Prior to Ownership  Which could Have Material
                         Adverse Effect with Respect to Environmental Matters

Schedule 4.1(AA)         Tax Reports Matters

Schedule 4.1(CC)         Derivative Contracts,  including a list of any assets
                         pledged as security for such Derivative Contracts

Schedule 4.1(EE)(1)      Employment  Contracts Requiring Payment In Connection
                         with Termination

Schedule 4.1(EE)(2)      Leases with Aggregate Annual Rent Exceeding $10,000

Schedule 4.1(EE)(3)      Material Contracts with Affiliates

USBN Disclosures
----------------
Schedule 4.2(C)          Shares

Schedule 4.2(F)          No Defaults
</TABLE>



                                     A - iv


<PAGE>   100



<TABLE>
<CAPTION>
Company Disclosures
-------------------
<S>                                         <C>
Schedule 4.2(G)          Financial Reports

Schedule 4.2(H)          No Events Causing Material Adverse Effect

Schedule 4.2(I)          Litigation, Regulatory Action

Schedule 4.2(L)          Derivative Contracts,  including a list of any assets
                         pledged as security for such Derivative Contracts
</TABLE>




                                     A - v


<PAGE>   101


                          AGREEMENT AND PLAN OF MERGER

        AGREEMENT AND PLAN OF MERGER, dated as of the 10th day of November, 1998
(this "Plan"), is between UNITED SECURITY BANCORPORATION ("USBN"), BANCWEST
FINANCIAL CORPORATION ("Bancwest"), and BANK OF THE WEST (the "Bank").

                                    RECITALS

        (A) BANCWEST. Bancwest is a corporation duly organized and existing in
good standing under the laws of the State of Washington, with its principal
executive offices located in Walla Walla, Washington. Bancwest is a registered
bank holding company under the Bank Holding Company Act of 1956, as amended. As
of the date of this Plan, Bancwest has 1,000,000 authorized shares of common
stock, no par value per share ("Bancwest Common Stock") (no other class of
capital stock being authorized), of which 364,281 shares of Bancwest Common
Stock are issued and outstanding, no other class of capital stock being
authorized. As of the date of this Plan, Bancwest had 72,000 shares of Bancwest
Common Stock reserved for issuance under director and employee stock option
plans pursuant to which options covering 26,984 shares of Bancwest Common Stock
are outstanding as of the date of this Plan.

        (B) BANK OF THE WEST. Bank of the West is a banking corporation duly
organized and existing in good standing under the laws of the State of
Washington. As of the date of this Plan, Bank of the West has 500,000 authorized
shares of common stock, no par value per share ("Bank of the West Common Stock")
(no other class of capital stock being authorized), of which 364,281 shares of
Bank of the West Common Stock are issued and outstanding. All of the issued and
outstanding shares of Bank of the West Common Stock are owned by Bancwest, the
sole shareholder of Bank of the West. As of September 30, 1998, Bank of the West
had capital of $11,651,076 divided into common stock of $364,281 surplus of
$3,799,029 and undivided profits of $7,487,766.

        (C) USBN. USBN is a corporation duly organized and existing in good
standing under the laws of the State of Washington, with its principal executive
offices located in Spokane, Washington. USBN is a registered bank holding
company under the Bank Holding Company Act of 1956, as amended. As of the date
of this Plan, USBN has 15,000,000 authorized shares of common stock, no par
value per share ("USBN Common Stock") (no other class of capital stock being
authorized), of which 4,546,722 shares of USBN Common Stock are issued and
outstanding. As of the date of this Plan, USBN had 300,000 shares of USBN Common
Stock reserved for issuance under stock option plans pursuant to which options
covering 192,860 shares of USBN Common Stock are outstanding as of the date of
this Plan.

        (D) VOTING AGREEMENT. As a condition and an inducement to USBN's
willingness to enter into this Plan, the directors and officers of Bank of the
West and Bancwest have entered into agreements in the forms attached to this
Plan as Exhibit A and Exhibit B, pursuant to which, among other things, each
such individual has agreed to vote his or her shares of Bancwest Common Stock in
favor of approval of the actions contemplated by this Plan at the Meetings (as
defined below) and to refrain from competing with USBN.

        (E) STOCK OPTION AGREEMENT. Immediately after the execution and delivery
of this Plan, as a condition and an inducement to USBN's willingness to enter
into this Plan, Bancwest and USBN are entering into a Stock Option Agreement
(the "Stock Option Agreement") in the form attached to this Plan as Exhibit C,
pursuant to which Bancwest is granting to USBN an option to purchase, under
certain circumstances, shares of Bancwest Common Stock.

        (F) RIGHTS, ETC. Except as Previously Disclosed (as defined below) in
Schedule 4.l(C), Schedule 2.8, or paragraph (A) of the Recitals to this Plan,
or as authorized by this Plan: there are no shares of capital stock of Bancwest
or Bank of the West authorized and reserved for issuance; neither Bancwest nor



                                     A - 1

<PAGE>   102

Bank of the West has any Rights (as defined below) issued or outstanding; and
neither Bancwest nor Bank of the West has any commitment to authorize, issue or
sell any such shares or any Rights. The term "Rights" means securities or
obligations convertible into or exchangeable for, or giving any Person any right
to subscribe for or acquire, or any options, calls or commitments relating to,
shares of capital stock. There are no preemptive rights with respect to Bancwest
Common Stock.

        (G) APPROVALS. At meetings of the respective Boards of Directors of
Bancwest, Bank of the West, and USBN, each such Board has approved and
authorized the execution of this Plan in counterparts.

        In consideration of their mutual promises and obligations, the Parties
further agree as follows:

                                   DEFINITIONS

        (A) DEFINITIONS. Capitalized terms used in this Plan have the following
meanings:

        "Acquisition Proposals" has the meaning assigned to such term in Section
5.19.

        "Adjusted Loans" means all loans and other extensions of credit by Bank
of the West other than (1) that portion of Small Business Administration loans
or the guaranteed portions of other loans guaranteed by the U.S. Government or
any of its agencies, and (2) single-family residential loans in the process of
being sold.

        "Additional Shares" means the number equal to (1) Bancwest's net income
(determined in accordance with GAAP) during the period commencing on January 1,
1999 and ending on the Effective Date, divided by (2) the Average Closing Price.

        "Adjustment Factor" means the number equal to the Additional Shares
divided by the number of outstanding shares of Bancwest Common Stock on the
Effective Date.

         "Appraisal Laws" has the meaning assigned to such term in Section 1.2.

        "Asset Classification" has the meaning assigned to such term in Section
4.1(T).

        "Average Closing Price" means the price equal to the average (rounded to
the nearest penny) of each Daily Sales Price of USBN Common Stock for the ten
(10) consecutive trading days on which at least 2,000 shares of USBN Common
Stock are traded, with the last such trading day being the fifth day preceding
the Effective Date.

        "Bancwest Directors" has the meaning assigned to such term in Section
5.18(A).

        "Bancwest Common Stock" has the meaning assigned to such term in
paragraph (A) of the Recitals.

        "Bancwest Meeting" has the meaning assigned to such term in Section 5.2.

        "Bancwest Option" has the meaning assigned to such term in Section 2.8.

        "Bank Financial Reports" has the meaning assigned to such term in
Section 4.1(H).

        "Bank of the West" has the meaning assigned to such term in the first
paragraph of this Plan.

        "Bank of the West Common Stock" has the meaning assigned to such term in
paragraph (B) of the Recitals.



                                     A - 2


<PAGE>   103


        "Business Day" means any day other than a Saturday, Sunday, or legal
holiday in the State of Washington.

        "Capital" means capital stock, surplus and retained earnings determined
in accordance with GAAP.

        "Code" has the meaning assigned to such term in Section 4.1(Q)(2).

        "Company" has the meaning assigned to such term in the first paragraph
to this Plan.

        "Compensation and Benefit Plans" has the meaning assigned to such term
in Section 4.1(Q)(1).

        "Continuing Corporation" has the meaning assigned to such term in
Section 1.1(A).

        "Control" with respect to any Person means the possession, directly or
indirectly, of the power to direct or cause the direction of the management and
policies of such Person, whether through the ownership of voting interests, by
contract, or otherwise.

         "Daily Sales Price" for any trading day shall be equal to the average
(rounded to four decimals) of the daily high and low trading prices per share of
USBN Common Stock on the NASDAQ Stock Market reporting system, as reported in
The Wall Street Journal.

        "Department" means the Department of Financial Institutions of the State
of Washington.

        "Derivatives Contract" means an exchange-traded or over-the-counter
swap, forward, future, option, cap, floor or collar financial contract or any
other contract that (1) is not included on the balance sheet of the Holding
Company Financial Reports or the USBN Financial Reports, as the case may be, and
(2) is a derivative contract (including various combinations thereof).

        "Dissenting Shares" means the shares of Bancwest Common Stock held by
those shareholders of Bancwest who have timely and properly exercised their
dissenters' rights in accordance with the Appraisal Laws.

        "Effective Date" has the meaning assigned to such term in Section 1.3.

        "Eligible Bancwest Common Stock" means shares of Bancwest Common Stock
other than Exception Shares and Dissenting Shares.

        "Employment Agreement" shall mean Exhibit D.

        "Environmental Law" means (1) any federal, state, and/or local law,
statute, ordinance, rule, regulation, code, license, permit, authorization,
approval, consent, legal doctrine, order, judgment, decree, injunction,
requirement or agreement with any governmental entity, relating to (a) the
protection, preservation or restoration of the environment (including air, water
vapor, surface water, groundwater, drinking water supply, surface land,
subsurface land, plant and animal life or any other natural resource) or to
human health or safety, or (b) the exposure to, or the use, storage, recycling,
treatment, generation, transportation, processing, handling, labeling,
production, release or disposal of Hazardous Material, in each case as amended
and as now in effect, including the Federal Comprehensive Environmental
Response, Compensation, and Liability Act of 1980, the Superfund Amendments and
Reauthorization Act, the Federal Water Pollution Control Act of 1972, the
Federal Clean Air Act, the Federal Clean Water Act, the Federal Resource
Conservation and Recovery Act of 1976 (including the Hazardous and Solid Waste
Amendments thereto), the Federal Solid Waste Disposal and the Federal Toxic
Substances Control Act, and the Federal Insecticide, Fungicide and Rodenticide
Act, the Federal Occupational Safety and Health Act of 1970, and (2) any common
law or equitable doctrine (including injunctive relief and tort doctrines such
as negligence, 



                                     A - 3

<PAGE>   104


nuisance, trespass and strict liability) that may impose liability or
obligations for injuries or damages due to, or threatened as a result of, the
presence of or exposure to any Hazardous Material.

        "ERISA" has the meaning assigned to such term in Section 4.1(Q)(2).

        "ERISA Affiliate" has the meaning assigned to such term in Section
4.1(Q)(3).

        "ERISA Plans" has the meaning assigned to such term in Section
4.1(Q)(2).

        "Exception Shares" means shares held by any of Bancwest's Subsidiaries
or by USBN or any of its Subsidiaries, in each case other than in a fiduciary
capacity or as a result of debts previously contracted.

        "Exchange Act" means the Securities Exchange Act of 1934, as amended,
together with the rules and regulations promulgated under such statute.

        "Exchange Agent" has the meaning assigned to such term in Section 2.4.

        "Exchange Ratio" has the meaning assigned to such term in Section
2.1(B).

        "FDIC" means the Federal Deposit Insurance Corporation.

        "Financial Reports" has the meaning assigned to such term in Section
4.1(H).

        "Federal Reserve Board" means the Board of Governors of the Federal
Reserve System.

        "GAAP" means generally accepted accounting principles consistently
applied.

        "Hazardous Material" means any substance presently listed, defined,
designated or classified as hazardous, toxic, radioactive or dangerous, or
otherwise regulated, under any Environmental Law, whether by type or quantity,
including any oil or other petroleum product, toxic waste, pollutant,
contaminant, hazardous substance, toxic substance, hazardous waste, special
waste or petroleum or any derivative or by-product thereof, radon, radioactive
material, asbestos, asbestos containing material, urea formaldehyde foam
insulation, lead and polychlorinated biphenyl.

        "Holding Company Financial Reports" has the meaning assigned to such
term in Section 4.1(H).

        "Indemnified Party" has the meaning assigned to such term in Section
5.17(A).

        "Loan/Fiduciary Property" means any property owned or controlled by
Bancwest or any of its Subsidiaries or in which Bancwest or any of its
Subsidiaries holds a security or other interest, and, where required by the
context, includes any such property where Bancwest or any of its Subsidiaries
constitutes the owner or operator of such property, but only with respect to
such property.

        "Material Adverse Effect" means, with respect to any Party, an event,
occurrence or circumstance (including (i) the making of any provisions for
possible loan and lease losses, write-downs of other real estate owned and
taxes, and (ii) any breach of a representation or warranty contained in this
Plan by such Party) that (a) has or is reasonably likely to have a material
adverse effect on the financial condition, results of operations, business or
prospects of such Party and its Subsidiaries, taken as a whole, or (b) would
materially impair such Party's ability to perform its obligations under this
Plan or the consummation of any of the transactions contemplated by this Plan.

        "Meetings" has the meaning assigned to such term in Section 5.3.



                                      A - 4


<PAGE>   105


        "Merger" has the meaning assigned to such term in Section 1.1(A).

        "Multiemployer Plans" has the meaning assigned to such term in Section
4.1(Q)(2).

        "NASDAQ" means the National Association of Securities Dealers Automated
Quotations system.

        "Option" has the meaning assigned to such term in the Stock Option
Agreement.

        "Option Shares" has the meaning assigned to such term in the Stock
Option Agreement.

        "Participation Facility" means any facility in which Bancwest or any of
its Subsidiaries participates in the management and, where required by the
context, includes the owner or operator of such facility.

        "Party" means a party to this Plan.

        "Pension Plan" has the meaning assigned to such term in Section
4.1(Q)(2).

        "Person" means any individual, corporation (including any non-profit
corporation), general or limited partnership, limited liability company, joint
venture, estate, trust, association, organization, labor union, governmental
body, or other entity.

        "Plan" means this Agreement and Plan of Merger, together with all
Exhibits and Schedules to this Plan.

        "Previously Disclosed" means information provided by a Party in a
Schedule that is delivered by that Party to the other Party contemporaneously
with the execution of this Plan.

        "Proxy Statement" has the meaning assigned to such term in Section 5.2.

        "Registration Statement" has the meaning assigned to such term in
Section 5.2.

        "Regulatory Authorities" means federal or state governmental agencies,
authorities or departments charged with the supervision or regulation of
depository institutions or engaged in the insurance of deposits.

        "RCW" means the Revised Code of Washington, as amended.

        "Rights" has the meaning assigned to such term in paragraph (G) of the
Recitals to this Plan.

        "Securities Act" means the Securities Act of 1933, as amended, together
with the rules and regulations promulgated under such statute.

        "SEC" means the Securities and Exchange Commission.

        "Subsidiary" means, with respect to any entity, each partnership,
limited liability company, or corporation the majority of the outstanding
partnership interests, membership interests, capital stock or voting power of
which is (or upon the exercise of all outstanding warrants, options and other
rights would be) owned, directly or indirectly, at the time in question by such
entity.

        "Tax Returns" has the meaning assigned to such term in Section 4.1(AA).



                                     A - 5

<PAGE>   106


        "Taxes" means federal, state, local or foreign income, gross receipts,
windfall profits, severance, property, production, sales, use, license, excise,
franchise, employment, withholding or similar taxes imposed on the income,
properties or operations of the respective Party or its Subsidiaries, together
with any interest, additions, or penalties with respect thereto and any interest
in respect of such additions or penalties.

        "Termination Date" has the meaning assigned to such term in Section 1.3.

        "Third Party" means a person within the meaning of Sections 3(a)(9) and
13(d)(3) of the Exchange Act, excluding (1) Bancwest or any Subsidiary of
Bancwest, and (2) USBN or any Subsidiary of USBN.

        "USBN" has the meaning assigned to such term in the first paragraph of
this Plan.

        "USBN Common Stock" has the meaning assigned to such term in paragraph
(C) of the Recitals.

        "USBN Meeting" has the meaning assigned to such term in Section 5.2.

        "USBN Transaction" means: (1) a merger, consolidation or similar
transaction involving USBN, where USBN is not the corporation surviving such
transaction or where a change of control of USBN is otherwise effected, (2) the
disposition, by sale, lease, exchange or otherwise, of assets or deposits of
USBN or any of its significant subsidiaries representing in either case 25% or
more of the consolidated assets or deposits of USBN and its subsidiaries, or (3)
the issuance, sale or other disposition (including by way of merger,
consolidation, share exchange or any similar transaction) of securities
representing 25% or more of the voting power of USBN or any of its significant
subsidiaries other than the issuance of USBN Common Stock upon the exercise of
outstanding options or the conversion of outstanding convertible securities of
USBN.

        (B) GENERAL INTERPRETATION. Except as otherwise expressly provided in
this Plan or unless the context clearly requires otherwise, the terms defined in
this Plan include the plural as well as the singular; the words "hereof,"
"herein," "hereunder," "in this Plan" and other words of similar import refer to
this Plan as a whole and not to any particular Article, Section or other
subdivision; and references in this Plan to Articles, Sections, Schedules, and
Exhibits refer to Articles and Sections of and Schedules and Exhibits to this
Plan. Unless otherwise stated, references to Subsections refer to the
Subsections of the Section in which the reference appears. All pronouns used in
this Plan include the masculine, feminine and neuter gender, as the context
requires. All accounting terms used in this Plan that are not expressly defined
in this Plan have the respective meanings given to them in accordance with GAAP.

                                    I. MERGER

        1.1 THE MERGER. Subject to the provisions of this Plan, on the Effective
Date:

                (A) CONTINUING CORPORATION. Bancwest shall be merged with and
into USBN pursuant to the terms and conditions set forth herein (the "Merger").
Upon consummation of the Merger, the separate existence of Bancwest shall cease
and USBN shall continue as the Continuing Corporation.

                (B) CERTIFICATE OF INCORPORATION AND BYLAWS. The certificate of
incorporation and bylaws of USBN, in effect immediately prior to the Effective
Date, shall become the certificate of incorporation and bylaws of the Continuing
Corporation. The directors and officers of USBN in office immediately prior to
the Merger becoming effective shall be the directors and officers of the
Continuing Corporation, together with such additional directors and officers as
may thereafter be elected, who shall hold office until such time as their
successors are elected and qualified; provided, however, that 



                                     A - 6

<PAGE>   107


three directors of Bancwest shall be appointed to the Board of Directors of the
Continuing Corporation pursuant to Section 5.18.

                (C) EFFECTS OF THE MERGER. The separate existence of Bancwest
shall cease, and Bancwest shall be merged with and into USBN which, as the
Continuing Corporation, shall thereupon and thereafter possess all of the
assets, rights, privileges, appointments, powers, licenses, permits and
franchises of the two merged corporations, whether of a public or a private
nature, and shall be subject to all of the liabilities, restrictions and duties
of both USBN and Bancwest. Bank of the West shall continue as a wholly owned
subsidiary of the Continuing Corporation for at least three (3) years following
the Effective Date.

                (D) TRANSFER OF ASSETS. All rights, assets, licenses, permits,
franchises and interests of USBN and Bancwest in and to every type of property,
whether real, personal, or mixed, whether tangible or intangible, shall be
deemed to be vested in USBN as the Continuing Corporation by virtue of the
Merger becoming effective and without any deed or other instrument or act of
transfer whatsoever.

                (E) ASSUMPTION OF LIABILITIES. The Continuing Corporation shall
become and be liable for all debts, liabilities, obligations and contracts of
USBN as well as those of Bancwest, whether the same shall be matured or
unmatured; whether accrued, absolute, contingent or otherwise; and whether or
not reflected or reserved against in the balance sheets, other financial
statements, books of account or records of USBN or Bancwest.

        1.2 DISSENTING SHARES. Notwithstanding anything to the contrary in this
Plan, each Dissenting Share whose holder, as of the Effective Date of the
Merger, has not effectively withdrawn or lost his dissenters' rights under RCW
23B.13 (the "Appraisal Laws") shall not be converted into or represent a right
to receive USBN Common Stock, but the holder of such Dissenting Share shall be
entitled only to such rights as are granted by the Appraisal Laws, unless and
until such holder shall have failed to perfect or shall have effectively
withdrawn or lost the right to payment under the Appraisal Laws, in which case
each such share shall be deemed to have been converted at the Effective Date
into the right to receive USBN Common Stock without any interest thereon. Each
holder of Dissenting Shares who becomes entitled to payment for his Bancwest
Common Stock pursuant to the provisions of the Appraisal Laws shall receive
payment for such Dissenting Shares from USBN (but only after the amount thereof
shall have been agreed upon or finally determined pursuant to the Appraisal
Laws).

        1.3 EFFECTIVE DATE Unless the Parties agree upon another date, the
"Effective Date" will be the tenth Business Day after the fulfillment or waiver
of each condition precedent set forth in, and the granting of each approval (and
expiration of any waiting period) required by, Article VI. If the Merger is not
consummated in accordance with this Plan on or prior to June 30, 1999 (the
"Termination Date"), Bancwest or USBN may terminate this Plan in accordance with
Article VII. On the Effective Date, USBN and Bancwest shall execute and deliver
to the Secretary of State of the State of Washington articles of merger in
accordance with applicable law.

                                II. CONSIDERATION

        2.1 EXCHANGE CONSIDERATION. Subject to the provisions of this Plan, on
the Effective Date:

                (A) OUTSTANDING USBN COMMON STOCK. The shares of USBN Common
Stock issued and outstanding immediately prior to the Effective Date shall, on
and after the Effective Date, remain as issued and outstanding shares of USBN
Common Stock.

                (B) OUTSTANDING BANCWEST COMMON STOCK. Each share of Eligible
Bancwest Common Stock issued and outstanding immediately prior to the Effective
Date shall, by virtue of 



                                     A - 7

<PAGE>   108


the Merger, automatically and without any action on the part of the holder of
such share, be exchanged for the right to receive a number of shares of USBN
Common Stock equal to the sum of 4.7038 plus the Adjustment Factor (as adjusted,
if applicable, pursuant to Section 2.5) (the "Exchange Ratio").

        2.2 SHAREHOLDER RIGHTS; STOCK TRANSFERS. On the Effective Date, holders
of Bancwest Common Stock shall cease to be, and shall have no rights as,
shareholders of Bancwest, other than to receive the consideration provided under
this Article II. After the Effective Date, there shall be no transfers on the
stock transfer books of Bancwest or the Continuing Corporation of the shares of
Bancwest Common Stock that were issued and outstanding immediately prior to the
Effective Date.

        2.3 FRACTIONAL SHARES. Notwithstanding any other provision of this Plan,
no fractional shares of USBN Common Stock and no certificates or scrip therefor,
or other evidence of ownership thereof, will be issued in the Merger. Any holder
of Bancwest Common Stock who would otherwise be entitled to a fractional share
of USBN Common Stock will receive an amount in cash determined by multiplying
such fraction by the Average Closing Price.

        2.4 EXCHANGE PROCEDURES. As promptly as practicable after the Effective
Date, USBN shall send or cause to be sent to each former shareholder of Bancwest
of record immediately prior to the Effective Date transmittal materials for use
in exchanging such shareholder's certificates for Bancwest Common Stock for the
consideration set forth in this Article II. The certificates representing the
shares of USBN Common Stock into which shares of such shareholder's Bancwest
Common Stock are converted on the Effective Date, any fractional share checks
that such shareholder shall be entitled to receive, and any dividends paid on
such shares of USBN Common Stock for which the record date for determination of
shareholders entitled to such dividends is on or after the Effective Date, will
be delivered to such shareholder only upon delivery to USBN's exchange agent
(the "Exchange Agent") of the certificates representing all of such shares of
Bancwest Common Stock (or indemnity satisfactory to USBN and the Exchange Agent,
in their judgment, if any of such certificates are lost, stolen or destroyed).
No interest will be paid on any such fractional share checks or dividends to
which the holder of such shares shall be entitled to receive upon such delivery.
Certificates surrendered for exchange by any person constituting an "affiliate"
of Bancwest for purposes of Rule 145 of the Securities Act shall not be
exchanged for certificates representing USBN Common Stock until USBN has
received a written agreement from such person as specified in Section 5.9.

        2.5 EXCHANGE RATIO ADJUSTMENT. In the event that Bancwest or USBN
changes the number of shares of their common stock issued and outstanding prior
to the Effective Date as a result of a stock split, stock dividend,
recapitalization or similar transaction with respect to outstanding common stock
and the record date therefor shall be prior to the Effective Date, the Exchange
Ratio shall be adjusted proportionately so as not to dilute the shareholders of
Bancwest or otherwise affect the amount or kind of consideration provided for
under this Plan.

        2.6 EXCEPTION SHARES. Each of the Exception Shares of Bancwest Common
Stock shall be canceled and retired upon consummation of the Merger, and no
consideration shall be issued in exchange therefor.

        2.7 RESERVATION OF RIGHT TO REVISE TRANSACTION. In its sole discretion,
and notwithstanding any other provision in this Plan to the contrary, USBN may
at any time change the method of effecting its acquisition of Bancwest and Bank
of the West; provided, however, that (A) no such change shall alter or change
the amount or kind of consideration to be issued to holders of Bancwest Common
Stock as provided for in this Plan, (B) no such change shall adversely affect
the tax treatment to Bancwest shareholders as a result of receiving such
consideration, and (C) no delay caused by such a change shall be the basis upon
which USBN terminates this Plan pursuant to Section 7.1(C). If USBN elects to
change the method of acquisition pursuant to this section, and as a result the
Merger will not be accounted for on a pooling-of-interests basis, USBN and
Bancwest must each first waive their pooling condition in Section 



                                     A - 8

<PAGE>   109


6.1(H). If USBN elects to change the method of acquisition and both USBN and
Bancwest have waived their pooling condition, if required, Bancwest and Bank of
the West will cooperate with and assist USBN with any necessary amendment to
this Plan, and with the preparation and filing of such applications, documents,
instruments and notices as may be necessary or desirable, in the opinion of
counsel for USBN, to obtain all necessary shareholder approvals and approvals of
any regulatory agency, administrative body or other governmental entity.

        2.8 OPTIONS. On the Effective Date, by virtue of the Merger, and without
any action on the part of any holder of an option, each option granted by
Bancwest to purchase shares of Bancwest Common Stock ("Bancwest Option") that is
then outstanding and unexercised shall be converted into and become an option to
purchase USBN Common Stock ("USBN Option") on the same terms and conditions as
are in effect with respect to Bancwest Option immediately prior to the Effective
Date, except that (A) each such USBN Option may be exercised solely for shares
of USBN Common Stock, (B) the number of shares of USBN Common Stock subject to
such USBN Option shall be equal to the number of shares of Bancwest Common Stock
subject to such Option immediately prior to the Effective Date multiplied by the
Exchange Ratio, the product being rounded, if necessary, up or down to the
nearest whole share, and (C) the per share exercise price under each such USBN
Option shall be adjusted by dividing the per share exercise price of Bancwest
Option by the Exchange Ratio, and rounding up or down to the nearest cent. The
number of shares of Bancwest Common Stock that are issuable upon exercise of
Options as of the date of this Plan are Previously Disclosed in Schedule 2.8.
Following the Effective Date, USBN shall use its best efforts to ensure that the
shares of USBN Common Stock to be issued upon the exercise of USBN Options are
properly registered pursuant to the Securities Act.

                        III. ACTIONS PENDING CONSUMMATION

        Unless otherwise agreed to in writing by USBN, each of Bancwest and Bank
of the West shall conduct its and each of its Subsidiaries' business in the
ordinary and usual course consistent with past practice and shall use its best
efforts to maintain and preserve its and each of its Subsidiaries' business
organization, employees and advantageous business relationships and retain the
services of its and each of its Subsidiaries' officers and key employees
identified by USBN, and neither Bancwest nor Bank of the West, without the prior
written consent of USBN, will (or cause or allow any of it Subsidiaries to):

        3.1 CAPITAL STOCK. Except for or as otherwise expressly permitted by
this Plan, or Bancwest Options, or as Previously Disclosed in Schedule 4.1(C),
issue, sell or otherwise permit to become outstanding any additional shares of
capital stock of Bancwest, Bank of the West or any of their Subsidiaries, or any
Rights with respect thereto, or enter into any agreement with respect to the
foregoing, or permit any additional shares of Bancwest Common Stock to become
subject to grants of employee stock options, stock appreciation rights or
similar stock-based employee compensation rights.

        3.2 DIVIDENDS, ETC. Make, declare or pay any dividend on or in respect
of, or declare or make any distribution on, or directly or indirectly combine,
redeem, reclassify, purchase or otherwise acquire, any shares of its capital
stock or, other than as permitted in or contemplated by this Plan or the Stock
Option Agreement, authorize the creation or issuance of, or issue, any
additional shares of its capital stock or any Rights with respect thereto.

        3.3 INDEBTEDNESS; LIABILITIES; ETC. Other than in the ordinary course of
business consistent with past practice, incur any indebtedness for borrowed
money, assume, guarantee, endorse or otherwise as an accommodation become
responsible or liable for the obligations of any other individual, corporation
or other entity.

        3.4 LINE OF BUSINESS; OPERATING PROCEDURES; ETC. Except as may be
directed by any regulatory agency, (A) change its lending, investment, liability
management or other material banking policies in any material respect, except
such changes as are in accordance and in an effort to 



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comply with Section 5.10, or (B) commit to incur any further capital
expenditures beyond those Previously Disclosed in Schedule 3.4 other than in the
ordinary course of business and not exceeding $25,000 individually or $75,000 in
the aggregate.

        3.5 LIENS AND ENCUMBRANCES. Impose, or suffer the imposition, on any
shares of stock of any of its Subsidiaries, any lien, charge or encumbrance, or
permit any such lien, charge or encumbrance to exist.

        3.6 COMPENSATION; EMPLOYMENT AGREEMENTS; ETC. Except as Previously
Disclosed in Schedule 3.6, enter into or amend any employment, severance or
similar agreement or arrangement with any of its directors, officers or
employees, or grant any salary or wage increase, amend the terms of any Bancwest
Option or increase any employee benefit (including incentive or bonus payments),
except normal individual increases in regular compensation to employees in the
ordinary course of business consistent with past practice.

        3.7 BENEFIT PLANS. Except as Previously Disclosed in Schedule 3.7, enter
into or modify (except as may be required by applicable law) any pension,
retirement, stock option, stock purchase, savings, profit sharing, deferred
compensation, consulting, bonus, group insurance or other employee benefit,
incentive or welfare contract, plan or arrangement, or any trust agreement
related thereto, in respect of any of its directors, officers or other
employees, including taking any action that accelerates the vesting or exercise
of any benefits payable thereunder.

        3.8 CONTINUANCE OF BUSINESS. Dispose of or discontinue any portion of
its assets, business or properties, that is material to Bancwest and its
Subsidiaries taken as a whole, or merge or consolidate with, or acquire all or
any portion of, the business or property of any other entity that is material to
Bancwest and its Subsidiaries taken as a whole (except foreclosures or
acquisitions by Bank of the West in its fiduciary capacity, in each case in the
ordinary course of business consistent with past practice).

        3.9 AMENDMENTS. Amend its articles of incorporation or bylaws.

        3.10 CLAIMS. Settle any claim, litigation, action or proceeding
involving any liability for material money damages or restrictions upon the
operations of Bancwest or any of its Subsidiaries.

        3.11 CONTRACTS. Except as previously disclosed on Schedule 3.11, enter
into, renew, terminate or make any change in any material contract, agreement or
lease (excluding agreements and loans permitted under Section 3.12), except in
the ordinary course of business consistent with past practice with respect to
contracts, agreements and leases that are terminable by it without penalty on no
more than 60 days prior written notice.

        3.12 LOANS. Extend credit or account for loans and leases other than in
accordance with existing lending policies and accounting practices, except that
Bancwest shall not, without the prior consent of USBN's Chief Executive Officer
or chief credit administrator: (a) modify, restructure or renew any existing
nonperforming loan (defined as on non-accrual status, or 90 days or more past
due) or make any new loan to any Person if the amount of the resulting loan,
when aggregated with all other loans or extensions of credit to such Person
whose loan is non-performing (or which would be required to be aggregated for
loans-to-one-borrower limitations), would be in excess of $100,000; (b) make any
loan to an existing customer as of the date of this Plan in excess of
$1,000,000; or (c) make any loan to a new customer in excess of $500,000, except
that (i) single-family residential loans may be made in amounts that would not
exceed applicable FHLMC and FNMA limits, and (ii) such limits shall not apply to
SBA or other governmental or governmental agency guaranteed amounts.



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        3.13 TRANSACTION EXPENSES. Incur expenses in connection with the
transactions contemplated by this Plan that exceed $275,000 in the aggregate.

                       IV. REPRESENTATIONS AND WARRANTIES

        4.1 BANCWEST AND BANK OF THE WEST REPRESENTATIONS AND WARRANTIES. Each
of Bancwest and Bank of the West hereby represents and warrants to USBN as
follows:

                (A) RECITALS. The facts set forth in the Recitals of this Plan
with respect to Bancwest and its Subsidiaries are true and correct.

                (B) ORGANIZATION, STANDING AND AUTHORITY. Each of Bancwest and
its Subsidiaries is duly qualified to do business and is in good standing in the
States of the United States and foreign jurisdictions where the failure to be
duly qualified, individually or in the aggregate, is reasonably likely to have a
Material Adverse Effect on it. Each of Bancwest and its Subsidiaries has in
effect all federal state, local and foreign governmental authorizations
necessary for it to own or lease its properties and assets and to carry on its
business as it is now conducted, the absence of which, individually or in the
aggregate, is reasonably likely to have a Material Adverse Effect on it. Bank of
the West is an "insured depository institution" as defined in the Federal
Deposit Insurance Act, as amended, and applicable regulations under such
statute, and its deposits are insured by the Bank Insurance Fund of the FDIC.

                (C) SHARES. The outstanding shares of Bancwest and its
Subsidiaries' capital stock are validly issued and outstanding, fully paid and
nonassessable, and subject to no preemptive rights. Except as Previously
Disclosed in Schedule 4.1(C) and paragraph (A) of the Recitals, and as provided
under the Stock Option Agreement, there are no shares of capital stock or other
equity securities of Bancwest or its Subsidiaries outstanding and no outstanding
Rights with respect thereto.

                (D) BANCWEST SUBSIDIARIES. Bancwest has Previously Disclosed in
Schedule 4.1(D) a list of all of its Subsidiaries. Each of its Subsidiaries that
is a bank is an "insured depository institution" as defined in the Federal
Deposit Insurance Act, as amended, and applicable regulations under such
statute. No equity securities of any of its Subsidiaries are or may become
required to be issued (other than to Bancwest or one of its Subsidiaries) by
reason of any Rights with respect thereto. There are no contracts, commitments,
understandings or arrangements by which any of its Subsidiaries is or may be
bound to sell or otherwise issue any shares of such Subsidiary's capital stock,
and there are no contracts, commitments, understandings or arrangements relating
to the rights of Bancwest or its Subsidiaries, as applicable, to vote or to
dispose of such shares. All of the shares of capital stock of each of its
Subsidiaries held by Bancwest or one of its Subsidiaries are fully paid and
nonassessable and are owned by Bancwest or one of its Subsidiaries free and
clear of any charge, mortgage, pledge, security interest, restriction, claim,
lien or encumbrance. Each of its Subsidiaries is in good standing under the laws
of the jurisdiction in which it is incorporated or organized, and is duly
qualified to do business and in good standing in the jurisdictions where the
failure to be duly qualified is reasonably likely, individually or in the
aggregate, to have a Material Adverse Effect on it. Except as Previously
Disclosed in Schedule 4.1(D), it does not own beneficially, directly or
indirectly, any shares of any equity securities or similar interests of any
corporation, bank, partnership, joint venture, business trust, association or
other organization. In the case of representations by Bancwest, the deposits of
its Subsidiaries that are banks are insured by the Bank Insurance Fund of the
FDIC.

                (E) CORPORATE POWER. Each of Bancwest and its Subsidiaries has
the corporate power and authority to carry on its business as it is now being
conducted and to own all its material properties and assets.



                                     A - 11


<PAGE>   112


                (F) CORPORATE AUTHORITY. Subject to any necessary receipt of
approval by its shareholders referred to in Section 6.1, this Plan, the Stock
Option Agreement, and the Employment Agreement have been authorized by all
necessary corporate action of Bancwest and each of its Subsidiaries that is a
Party, and each such agreement is a valid and binding agreement of Bancwest and
such Subsidiaries, enforceable against Bancwest and such Subsidiaries in
accordance with its terms, subject to bankruptcy, insolvency and other laws of
general applicability relating to or affecting creditors' rights and to general
equity principles.

                (G) NO DEFAULTS. Subject to the approval by its shareholders
referred to in Section 6.1, the required regulatory approvals referred to in
Section 6.1, and the required filings under federal and state securities laws,
and except as Previously Disclosed in Schedule 4.1(G), the execution, delivery
and performance of this Plan and the Stock Option Agreement and the consummation
by Bancwest and each of its Subsidiaries that is a Party to the transactions
contemplated by this Plan and the Stock Option Agreement do not and will not (1)
constitute a breach or violation of, or a default under, any law, rule or
regulation or any judgment, decree, order, governmental permit or license, or
agreement, indenture or instrument of Bancwest or of any of its Subsidiaries or
to which Bancwest or any of its Subsidiaries or its or their properties is
subject or bound, which breach, violation or default is reasonably likely,
individually or in the aggregate, to have a Material Adverse Effect on it, (2)
constitute a breach or violation of, or a default under, the articles of
incorporation, charter or bylaws of it or any of its Subsidiaries, or (3)
require any consent or approval under any such law, rule, regulation, judgment,
decree, order, governmental permit or license or the consent or approval of any
other party to any such agreement, indenture or instrument, other than any such
consent or approval that, if not obtained, would not be reasonably likely,
individually or in the aggregate, to have a Material Adverse Effect on it.

                (H) FINANCIAL REPORTS. Except as Previously Disclosed in
Schedule 4.1(H), (1) as to Bancwest, its compiled consolidated balance sheets as
of December 31, 1997 and December 31, 1996, and the related statements of
income, changes in shareholders' equity and cash flows for the fiscal years
ended December 31, 1997 and December 31, 1996 (collectively, the "Holding
Company Financial Reports"), and (2) as to each of Bancwest's Subsidiaries that
is a bank, its call report for the fiscal year ended December 31, 1997, and all
other financial reports filed or to be filed subsequent to December 31, 1997, in
the form filed with the FDIC and the Department (in each case, the "Bank
Financial Reports" and together with the Holding Company Financial Reports, the
"Financial Reports") did not and will not contain any untrue statement of a
material fact or omit to state a material fact required to be stated therein or
necessary to make the statements made therein, in light of the circumstances
under which they were made, not misleading; and each of the balance sheets in or
incorporated by reference into the Financial Reports (including the related
notes and schedules thereto) fairly presents and will fairly present the
financial position of the entity or entities to which it relates as of its date,
and each of the statements of income and changes in shareholders' equity and
cash flows or equivalent statements in the Bank Financial Reports (including any
related notes and schedules thereto) fairly presents and will fairly present the
results of operations, changes in shareholders' equity and cash flows, as the
case may be, of the entity or entities to which it relates for the periods set
forth therein, in each case in accordance with GAAP during the periods involved,
except in each case as may be noted therein, subject to normal and recurring
year-end audit adjustments in the case of unaudited statements.

                (I) ABSENCE OF UNDISCLOSED LIABILITIES. Except as Previously
Disclosed on Schedule 4.1(I), neither Bancwest nor any of its Subsidiaries has
any obligation or liability (contingent or otherwise) that, individually or in
the aggregate, is reasonably likely to have a Material Adverse Effect on it,
except (1) as reflected in its Holding Company Financial Reports prior to the
date of this Plan, and (2) for commitments and obligations made, or liabilities
incurred, in the ordinary course of business consistent with past practice since
December 31, 1997. Except as Previously Disclosed on Schedule 4.1(I), since
December 31, 1997, neither Bancwest nor any of its Subsidiaries has incurred or
paid any obligation or liability (including any obligation or liability incurred
in connection with any acquisitions in which any 



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form of direct financial assistance of the federal government or any agency
thereof has been provided to any Subsidiary) that, individually or in the
aggregate, is reasonably likely to have a Material Adverse Effect on it.

                (J) NO EVENTS. Except as Previously Disclosed on Schedule
4.1(J), since December 31, 1997, no event has occurred that, individually or in
the aggregate, is reasonably likely to have a Material Adverse Effect on it.

                (K) PROPERTIES. Except as reserved against in its Holding
Company Financial Reports, Bancwest and each of its Subsidiaries have good and
marketable title, free and clear of all liens, encumbrances, charges, defaults,
or equities of any character, to all of the properties and assets, tangible and
intangible, reflected in its Holding Company Financial Reports as being owned by
Bancwest or its Subsidiaries as of the dates thereof other than those that,
individually or in the aggregate, are not reasonably likely to have a Material
Adverse Effect on it, except those sold or otherwise disposed of in the ordinary
course of business. All buildings and all material fixtures, equipment, and
other property and assets that are held under leases or subleases by Bancwest or
any of its Subsidiaries are held under valid leases or subleases enforceable in
accordance with their respective terms, other than any such exceptions to
validity or enforceability that, individually or in the aggregate, are not
reasonably likely to have a Material Adverse Effect on it.

                (L) LITIGATION; REGULATORY ACTION. Except as Previously
Disclosed in Schedule 4.l(L), no litigation, proceeding or controversy before
any court or governmental agency is pending that, individually or in the
aggregate, is reasonably likely to have a Material Adverse Effect on Bancwest or
any of its Subsidiaries or that alleges claims under any fair lending law or
other law relating to discrimination, including the Equal Credit Opportunity
Act, the Fair Housing Act, the Community Reinvestment Act and the Home Mortgage
Disclosure Act, and, to the best of its knowledge, no such litigation,
proceeding or controversy has been threatened; and except as Previously
Disclosed in Schedule 4.1(L), neither Bancwest nor any of its Subsidiaries or
any of its or their material properties or their officers, directors or
controlling persons is a party to or is subject to any order, decree, agreement,
memorandum of understanding or similar arrangement with, or a commitment letter
or similar submission to, any Regulatory Authority, and neither Bancwest nor any
of its Subsidiaries has been advised by any of such Regulatory Authorities that
such authority is contemplating issuing or requesting (or is considering the
appropriateness of issuing or requesting) any such order, decree, agreement,
memorandum or understanding, commitment letter or similar submission.

                (M) COMPLIANCE WITH LAWS. Except as Previously Disclosed in
Schedule 4.1(M), each of Bancwest and its Subsidiaries:

                (1)     has all permits, licenses, authorizations, orders and
                        approvals of, and has made all filings, applications and
                        registrations with, all Regulatory Authorities that are
                        required in order to permit it to own its businesses
                        presently conducted and that are material to the
                        business of it and its Subsidiaries taken as a whole;
                        all such permits, licenses, certificates of authority,
                        orders and approvals are in full force and effect and,
                        to its best knowledge, no suspension or cancellation of
                        any of them is threatened; and all such filings,
                        applications and registrations are current;

                (2)     has received no notification or communication from any
                        Regulatory Authority or the staff thereof (a) asserting
                        that Bancwest or any of its Subsidiaries is not in
                        compliance with any of the statutes, regulations or
                        ordinances which such Regulatory Authority enforces,
                        which, as a result of such noncompliance in any such
                        instance, individually or in the aggregate, is
                        reasonably likely to have a Material Adverse Effect 



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                        on Bancwest or its Subsidiaries, (b) threatening to
                        revoke any license, franchise, permit or governmental
                        authorization, which revocation, individually or in the
                        aggregate, is reasonably likely to have a Material
                        Adverse Effect on Bancwest or its Subsidiaries, or (c)
                        requiring any of Bancwest or its Subsidiaries (or any of
                        its or their officers, directors or controlling persons)
                        to enter into a cease and desist order, agreement or
                        memorandum of understanding (or requiring the board of
                        directors thereof to adopt any resolution or policy);

                (3)     is not required to give prior notice to any federal
                        banking or thrift agency of the proposed addition of an
                        individual to its board of directors or the employment
                        of an individual as a senior executive; and

                (4)     is in compliance in all material respects with all fair
                        lending laws or other laws relating to discrimination,
                        including the Equal Credit Opportunity Act, the Fair
                        Housing Act, the Community Reinvestment Act and the Home
                        Mortgage Disclosure Act.

                (N) MATERIAL CONTRACTS. Except as Previously Disclosed in
Schedule 4.1(N), none of Bancwest or its Subsidiaries, nor any of their
respective assets, businesses or operations, is a party to, or is bound or
affected by, or receives benefits under, any material contract or agreement or
amendment thereto (excluding extensions of credit made in the ordinary course of
business). Neither Bancwest nor any of its Subsidiaries is in default under any
contract, agreement, commitment, arrangement, lease, insurance policy or other
instrument to which it is a party, by which its respective assets, business or
operations may be bound or affected or under which it or any of its respective
assets, business or operations receives benefits, which default, individually or
in the aggregate, is reasonably likely to have a Material Adverse Effect on
Bancwest or its Subsidiaries, and there has not occurred any event that, with
the lapse of time or the giving of notice or both, would constitute such a
default. Except as Previously Disclosed in Schedule 4.1(N), neither Bancwest nor
any of its Subsidiaries is subject to or bound by any contract containing
covenants that limit the ability of Bancwest or any of its Subsidiaries to
compete in any line of business or with any Person or that involve any
restriction of geographical area in which, or method by which, Bancwest or any
of its Subsidiaries may carry on its business (other than as may be required by
law or any applicable Regulatory Authority).

                (O) REPORTS. Since January 1, 1993, each of Bancwest and its
Subsidiaries has filed all reports and statements, together with any amendments
required to be made with respect thereto, that it was required to file with (1)
the Department, (2) the FDIC, (3) the Federal Reserve Board, and (4) any other
Regulatory Authorities having jurisdiction with respect to Bancwest and its
Subsidiaries. As of their respective dates (and without giving effect to any
amendments or modifications filed after the date of this Plan with respect to
reports and documents filed before the date of this Plan), each of such reports
and documents, including the financial statements, exhibits and schedules
thereto, complied in all material respects with all of the statutes, rules and
regulations enforced or promulgated by the Regulatory Authority with which they
were filed and did not contain any untrue statement of a material fact or omit
to state any material fact necessary in order to make the statements made
therein, in light of the circumstances under which they were made, not
misleading.

                (P) NO BROKERS. Except as Previously Disclosed in Schedule
4.1(P), all negotiations relative to this Plan and the transactions contemplated
by this Plan have been carried on by it directly with the other Parties and no
action has been taken by it that would give rise to any valid claim against any
Party for a brokerage commission, finder's fee or other like payment.

                (Q) EMPLOYEE BENEFIT PLANS.

                        (1) Schedule 4.1(Q)(1) contains a complete list of all
        bonus, deferred compensation, pension, retirement, profit-sharing,
        thrift savings, employee stock ownership, stock bonus, stock purchase
        restricted stock and stock option plans, all employment or severance
        contracts, all medical, dental, health and life insurance plans, all
        other employee benefit plans, 




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        contracts or arrangements and any applicable "change of control" or
        similar provisions in any plan, contract or arrangement maintained or
        contributed to by Bancwest or any of its Subsidiaries for the benefit of
        employees, former employees, directors, former directors or their
        beneficiaries (the "Compensation and Benefit Plans"). True and complete
        copies of all Compensation and Benefit Plans of Bancwest and its
        Subsidiaries, including any trust instruments and/or insurance
        contracts, if any, forming a part thereof, and all amendments thereto,
        have been supplied to the other Parties.

                        (2) All "employee benefit plans" within the meaning of
        Section 3(3) of the Employee Retirement Income Security Act of 1974, as
        amended ("ERISA"), other than "multiemployer plans" within the meaning
        of Section 3(37) of ERISA ("Multiemployer Plans"), covering employees or
        former employees of Bancwest and its Subsidiaries (the "ERISA Plans"),
        to the extent subject to ERISA, are in substantial compliance with
        ERISA. Except as Previously Disclosed in Schedule 4.1(Q)(2) each ERISA
        Plan which is an "employee pension benefit plan" within the meaning of
        Section 3(2) of ERISA ("Pension Plan") and which is intended to be
        qualified under Section 401(a) of the Internal Revenue Code of 1986, as
        amended (the "Code") has received a favorable determination letter from
        the Internal Revenue Service, and it is not aware of any circumstances
        reasonably likely to result in the revocation or denial of any such
        favorable determination letter or the inability to receive such a
        favorable determination letter. There is no material pending or, to its
        knowledge, threatened litigation relating to the ERISA Plans. Neither
        Bancwest nor any of its Subsidiaries has engaged in a transaction with
        respect to any ERISA Plan that could subject Bancwest or any of its
        Subsidiaries to a tax or penalty imposed by either Section 4975 of the
        Code or Section 502(i) of ERISA in an amount which would be material.

                        (3) No liability under Subtitle C or D of Title IV of
        ERISA has been or is expected to be incurred by Bancwest or any of its
        Subsidiaries with respect to any ongoing, frozen or terminated
        "single-employer plan," within the meaning of Section 4001(a)(15) of
        ERISA, currently or formerly maintained by any of them, or the
        single-employer plan of any entity which is considered one employer with
        Bancwest under Section 4001(a)(15) of ERISA or Section 414 of the Code
        (an "ERISA Affiliate"). Neither Bancwest nor any of its Subsidiaries
        presently contributes to a Multiemployer Plan, nor have they contributed
        to such a plan within the past five calendar years. No notice of a
        "reportable event," within the meaning of Section 4043 of ERISA for
        which the 30-day reporting requirement has not been waived, has been
        required to be filed for any Pension Plan or by any ERISA Affiliate
        within the past 12-month period.

                        (4) All contributions required to be made under the
        terms of any ERISA Plan have been timely made. Neither any Pension Plan
        nor any single-employer plan of an ERISA Affiliate has an "accumulated
        funding deficiency"(whether or not waived) within the meaning of Section
        412 of the Code or Section 302 of ERISA. Neither Bancwest nor any of its
        Subsidiaries has provided, or is required to provide, security to any
        Pension Plan or to any single-employer plan of an ERISA Affiliate
        pursuant to Section 401(a)(29) of the Code.

                        (5) Under each Pension Plan which is a single-employer
        plan, as of the last day of the most recent plan year, the actuarially
        determined present value of all "benefit liabilities," within the
        meaning of Section 4001(a)(16) of ERISA (as determined on the basis of
        the actuarial assumptions contained in the plan's most recent actuarial
        valuation) did not exceed the then current value of the assets of such
        plan, and there has been no material change in the financial condition
        of such plan since the last day of the most recent plan year.

                        (6) Neither Bancwest nor any of its Subsidiaries has any
        obligations for retiree health and life benefits under any plan, except
        as set forth in Schedule 4.1(Q)(6). There are no 




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        restrictions on the rights of Bancwest or any of its Subsidiaries to
        amend or terminate any such plan without incurring any liability
        thereunder.

                        (7) Except as Previously Disclosed in Schedule
        4.l(Q)(7), neither the execution and delivery of this Plan nor the
        consummation of the transactions contemplated by this Plan will (a)
        result in any payment (including severance, unemployment compensation,
        golden parachute or otherwise) becoming due to any director or any
        employee of Bancwest or any of its Subsidiaries under any Compensation
        and Benefit Plan or otherwise from Bancwest or any of its Subsidiaries,
        (b) increase any benefits otherwise payable under any Compensation and
        Benefit Plan, or (c) result in any acceleration of the time of payment
        or vesting of any such benefit.

                (R) NO KNOWLEDGE. Bancwest and its Subsidiaries know of no
reason why the regulatory approvals referred to in Section 6.1(B) should not be
obtained.

                (S) LABOR AGREEMENTS. Neither Bancwest nor any of its
Subsidiaries is a party to or is bound by any collective bargaining agreement,
contract or other agreement or understanding with a labor union or labor
organization, nor is Bancwest or any of its Subsidiaries the subject of a
proceeding asserting that it or any such Subsidiary has committed an unfair
labor practice (within the meaning of the National Labor Relations Act) or
seeking to compel it or such Subsidiary to bargain with any labor organization
as to wages and conditions of employment, nor is there any strike or other labor
dispute involving it or any of its Subsidiaries pending or, to the best of its
knowledge, threatened, nor is it aware of any activity involving its or any of
the Subsidiaries' employees seeking to certify a collective bargaining unit or
engaging in any other organization activity.

                (T) ASSET CLASSIFICATION. Bancwest and its Subsidiaries have
Previously Disclosed in Schedule 4.1(T) a list, accurate and complete in all
material respects, of the aggregate amounts of loans, extensions of credit or
other assets of Bancwest and its Subsidiaries that have been classified by it as
of September 30, 1998 (the "Asset Classification"); and no amounts of loans,
extensions of credit or other assets that have been classified as of September
30, 1998 by any regulatory examiner as "Other Loans Specially Mentioned,"
'Substandard," "Doubtful" "Loss," or words of similar import are excluded from
the amounts disclosed in the Asset Classification, other than amounts of loans,
extensions of credit or other assets that were charged off by Bancwest or any
Subsidiary prior to September 30, 1998.

                (U) ALLOWANCE FOR POSSIBLE LOAN AND LEASE LOSSES. The allowance
for possible loan losses shown on the consolidated balance sheets in the
December 31, 1997 Holding Company Financial Reports of Bancwest and the
September 30, 1998, Bank Regulatory Reports was, and the allowance for possible
loan losses to be shown on subsequent Holding Company Financial Reports of
Bancwest was and will be, adequate under GAAP, in the reasonable opinion of
Bancwest's Board of Directors, to provide for possible losses, net of recoveries
relating to loans previously charged off, on loans outstanding (including
accrued interest receivable) as of the date thereof.

                (V) INSURANCE. Each of Bancwest and its Subsidiaries has taken
all requisite action (including the making of claims and the giving of notices)
pursuant to its directors' and officers' liability insurance policy or policies
in order to preserve all rights thereunder with respect to all matters that are
known to Bancwest, except for such matters that, individually or in the
aggregate, are not reasonably likely to have a Material Adverse Effect on
Bancwest or its Subsidiaries. Set forth in Schedule 4.l(V) is a list of all
insurance policies maintained by or for the benefit of Bancwest or its
Subsidiaries or their respective directors, officers, employees or agents.



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                (W) AFFILIATES. Except as Previously Disclosed in Schedule
4.1(W), to the best of Bancwest's knowledge, there is no person who, as of the
date of this Plan, may be deemed to be an "affiliate" of Bancwest as that term
is used in Rule 145 under the Securities Act.

                (X) STATE TAKEOVER LAWS, ARTICLES OF INCORPORATION. Bancwest and
its Subsidiaries have taken all necessary action to exempt this Plan and the
Stock Option Agreement and the transactions contemplated by this Plan and the
Stock Option Agreement from, and this Plan and the Stock Option Agreement and
such transactions are exempt from (1) any applicable state takeover laws,
including, but not limited to, RCW Ch. 23B.19, as amended, and (2) any
takeover-related provisions of Bancwest's and its Subsidiaries' articles of
incorporation.

                (Y) NO FURTHER ACTION. Bancwest and its Subsidiaries have taken
all action so that the entering into of this Plan and the Stock Option Agreement
and the consummation of the transactions contemplated by this Plan and the Stock
Option Agreement (including the Merger and the exercise of the Option), or any
other action or combination of actions, or any other transactions, contemplated
by this Plan and the Stock Option Agreement do not and will not (1) require a
vote of shareholders (other than as set forth in Section 6.1), or (2) result in
the grant of any rights to any Person under the articles of incorporation,
charter or bylaws of Bancwest or any of its Subsidiaries or under any agreement
to which Bancwest or any such Subsidiaries is a party, or (iii) restrict or
impair in any way the ability of the other Parties to exercise the rights
granted under this Plan or the Stock Option Agreement.

                (Z) ENVIRONMENTAL MATTERS.

                        (1) To Bancwest's knowledge, it and each of its
        Subsidiaries, the Participation Facilities and the Loan/Fiduciary
        Properties are, and have been, in compliance with all Environmental
        Laws, except for instances of noncompliance that are not reasonably
        likely, individually or in the aggregate, to have a Material Adverse
        Effect on Bancwest or its Subsidiaries.

                        (2) There is no proceeding pending or, to Bancwest's
        knowledge, threatened before any court, governmental agency or board or
        other forum in which Bancwest or any of its Subsidiaries or any
        Participation Facility has been, or with respect to threatened
        proceedings, reasonably would be expected to be, named as a defendant or
        potentially responsible party (a) for alleged noncompliance (including
        by any predecessor) with any Environmental Law, or (b) relating to the
        release or threatened release into the environment of any Hazardous
        Material, whether or not occurring at or on a site owned, leased or
        operated by Bancwest or any of its Subsidiaries or any Participation
        Facility, except for such proceedings pending or threatened that are not
        reasonably likely, individually or in the aggregate, to have a Material
        Adverse Effect on Bancwest or its Subsidiaries or have been Previously
        Disclosed in Schedule 4.1(Z)(2).

                        (3) There is no proceeding pending or, to Bancwest's
        knowledge, threatened before any court, governmental agency or board or
        other forum in which any Loan/Fiduciary Property (or Bancwest or any of
        its Subsidiaries in respect of any Loan/Fiduciary Property) has been, or
        with respect to threatened proceedings, reasonably would be expected to
        be, named as a defendant or potentially responsible party (a) for
        alleged noncompliance (including by any predecessor) with any
        Environmental Law, or (b) relating to the release or threatened release
        into the environment of any Hazardous Material, whether or not occurring
        at or on a Loan/Fiduciary Property, except for such proceedings pending
        or threatened that are not reasonably likely, individually or in the
        aggregate, to have a Material Adverse Effect on Bancwest or have been
        Previously Disclosed in Schedule 4.1(Z)(3).



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<PAGE>   118


                        (4) To Bancwest's knowledge, there is no reasonable
        basis for any proceeding of a type described in subparagraph (2) or (3)
        of this paragraph (Z), except as has been Previously Disclosed in
        Schedule 4.1(Z)(4).

                        (5) To Bancwest's knowledge, during the period of (a)
        ownership or operation by Bancwest or any of its Subsidiaries of any of
        their respective current properties, (b) participation in the management
        of any Participation Facility by Bancwest or any of its Subsidiaries, or
        (c) holding of a security or other interest in a Loan/Fiduciary Property
        by Bancwest or any of its Subsidiaries, there have been no releases of
        Hazardous Material in, on, under or affecting any such property,
        Participation Facility or Loan/Fiduciary Property, except for such
        releases that are not reasonably likely, individually or in the
        aggregate, to have a Material Adverse Effect on Bancwest or its
        Subsidiaries or have been Previously Disclosed in Schedule 4.1(Z)(5).

                        (6) To Bancwest's knowledge, prior to the period of (a)
        ownership or operation by Bancwest or any of its Subsidiaries of any of
        their respective current properties, (b) participation in the management
        of any Participation Facility by Bancwest or any of its Subsidiaries, or
        (c) holding of a security or other interest in a Loan/Fiduciary Property
        by Bancwest or any of its Subsidiaries, there were no releases of
        Hazardous Material in, on, under or affecting any such property,
        Participation Facility or Loan) Fiduciary Property, except for such
        releases that are not reasonably likely, individually or in the
        aggregate, to have a Material Adverse Effect on Bancwest or its
        Subsidiaries or have been Previously Disclosed in Schedule 4.1(Z)(6).

                (AA) TAX REPORTS. Except as Previously Disclosed in Schedule
4.1(AA), (1) all reports and returns with respect to Taxes that are required to
be filed by or with respect to Bancwest or its Subsidiaries, including
consolidated federal income tax returns of Bancwest and its Subsidiaries
(collectively, the "Tax Returns"), have been duly filed, or requests for
extensions have been timely filed and have not expired, for periods ended on or
prior to the most recent fiscal year-end, except to the extent all such failures
to file, taken together, are not reasonably likely to have a Material Adverse
Effect on Bancwest or its Subsidiaries, and such Tax Returns were true, complete
and accurate in all material respects, (2) all Taxes shown to be due on the Tax
Returns have been paid in full, (3) the Tax Returns have been examined by the
Internal Revenue Service or the appropriate state, local or foreign taxing
authority, or the period for assessment of the Taxes in respect of which such
Tax Returns were required to be filed has expired, (4) all Taxes due with
respect to completed and settled examinations have been paid in full, (5) no
issues have been raised by the relevant taxing authority in connection with the
examination of any of the Tax Returns which are reasonably likely, individually
or in the aggregate, to result in a determination that would have a Material
Adverse Effect on Bancwest or its Subsidiaries, except as reserved against in
the Holding Company Financial Reports of Bancwest, and (6) no waivers of
statutes of limitations (excluding such statutes that relate to years under
examination by the Internal Revenue Service) have been given by or requested
with respect to any Taxes of Bancwest or its Subsidiaries.

                (BB) ACCURACY OF INFORMATION. The statements with respect to
Bancwest and its Subsidiaries contained in this Plan and the Stock Option
Agreement, the Schedules and any other written documents executed and delivered
by or on behalf of Bancwest or any other Party pursuant to the terms of or
relating to this Plan are true and correct in all material respects, and such
statements and documents do not omit any material fact necessary to make the
statements contained therein, in light of the circumstances under which they
were made, not misleading.

                (CC) DERIVATIVES CONTRACTS. None of Bancwest or its Subsidiaries
is a party to or has agreed to enter into a Derivatives Contract or owns
securities that are referred to as "structured notes" except for those
Derivatives Contracts and structured notes Previously Disclosed in Schedule



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4.1(CC). Schedule 4.1(CC) includes a list of any assets of Bancwest or its
Subsidiaries that are pledged as security for each such Derivatives Contract.

                (DD) ACCOUNTING CONTROLS. Each of Bancwest and its Subsidiaries
has devised and maintained systems of internal accounting controls sufficient to
provide reasonable assurances that (1) all material transactions are executed in
accordance with management's general or specific authorization, (2) all material
transactions are recorded as necessary to permit the preparation of financial
statements in conformity with GAAP, and to maintain proper accountability for
items, (3) access to the material property and assets of Bancwest and its
Subsidiaries is permitted only in accordance with management's general or
specific authorization, and (4) the recorded accountability for items is
compared with the actual levels at reasonable intervals and appropriate action
is taken with respect to any differences.

                (EE) COMMITMENTS AND CONTRACTS. Neither Bancwest nor any of its
Subsidiaries is a party or subject to any of the following (whether written or
oral, express or implied):

                        (1) except for the Employment Agreement and as
        Previously Disclosed in Schedule 4.1(EE)(1), any employment contract or
        understanding (including any understandings or obligations with respect
        to severance or termination pay liabilities or fringe benefits) with any
        present or former officer, director or employee (other than those which
        are terminable at will by Bancwest or any such Subsidiary without any
        obligation on the part of Bancwest or any such Subsidiary to make any
        payment in connection with such termination);

                        (2) except as Previously Disclosed in Schedule
        4.1(EE)(2), any real or personal property lease with annual rental
        payments aggregating $10,000 or more; or

                        (3) except as Previously Disclosed in Schedule
        4.1(EE)(3), any material contract with any affiliate.

                (FF) OPTION SHARES. The Option Shares, if and when issued upon
exercise of the Option, will be validly issued, fully paid and nonassessable and
subject to no preemptive rights.

        4.2 USBN REPRESENTATIONS AND WARRANTIES. USBN hereby represents and
warrants to Bancwest and Bank of the West as follows:

                (A) RECITALS. The facts set forth in the Recitals of this Plan
with respect to USBN are true and correct.

                (B) ORGANIZATION, STANDING AND AUTHORITY. USBN is duly qualified
to do business and is in good standing in the States of the United States and
foreign jurisdictions where the failure to be duly qualified, individually or in
the aggregate, is reasonably likely to have a Material Adverse Effect on it.
Each of USBN and its Subsidiaries has in effect all federal state, local, and
foreign governmental authorizations necessary for it to own or lease its
properties and assets and to carry on its business as it is now conducted, the
absence of which, individually or in the aggregate, is reasonably likely to have
a Material Adverse Effect on USBN.

                (C) SHARES. The outstanding shares of USBN's capital stock are
validly issued and outstanding, fully paid and nonassessable, and subject to no
preemptive rights. Except as Previously Disclosed in Schedule 4.2(C), there are
no shares of capital stock or other equity securities of it or its Subsidiaries
outstanding and no outstanding Rights with respect thereto.




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                (D) CORPORATE POWER. USBN has the corporate power and authority
to carry on its business as it is now being conducted and to own all its
material properties and assets.

                (E) CORPORATE AUTHORITY. This Plan and the Stock Option
Agreement have been authorized by all necessary corporate action of USBN and
such agreement is a valid and binding agreement of USBN, enforceable against
USBN in accordance with its terms, subject to bankruptcy, insolvency and other
laws of general applicability relating to or affecting creditors' rights and to
general equity principles.

                (F) NO DEFAULTS. Subject to receipt of the required regulatory
approvals referred to in Section 6.1, and the required filings under federal and
state securities laws, and except as Previously Disclosed in Schedule 4.2(F),
the execution, delivery and performance of this Plan, Stock Option Agreement,
and the Employment Agreement and the consummation by USBN and each of its
Subsidiaries that is a Party of the transactions contemplated by this Plan does
not and will not (1) constitute a breach or violation of, or a default under,
any law, rule or regulation or any judgment, decree, order, governmental permit
or license, or agreement, indenture or instrument of USBN or of any of its
Subsidiaries or to which USBN or any of its Subsidiaries or its or their
properties is subject or bound, which breach, violation or default is reasonably
likely, individually or in the aggregate, to have a Material Adverse Effect on
USBN, (2) constitute a breach or violation of, or a default under, the articles
of incorporation, charter or bylaws of USBN or any of its Subsidiaries, or (3)
require any consent or approval under any such law, rule, regulation, judgment,
decree, order, governmental permit or license or the consent or approval of any
other party to any such agreement, indenture or instrument, other than any such
consent or approval that, if not obtained, would not be reasonably likely,
individually or in the aggregate, to have a Material Adverse Effect on USBN.

                (G) FINANCIAL REPORTS. Except as Previously Disclosed in
Schedule 4.2(G), its Annual Report on Form 10-K for the fiscal year ended
December 31, 1997, and all other documents filed or to be filed subsequent to
December 31, 1997 under Sections 13(a), 13(c), 14 or 15(d) of the Exchange Act,
in the form filed with the SEC (in each such case, the "USBN Financial
Reports"), did not and will not contain any untrue statement of a material fact
or omit to state a material fact required to be stated therein or necessary to
make the statements made therein, in light of the circumstances under which they
were made, not misleading; and each of the balance sheets in or incorporated by
reference into the USBN Financial Reports (including the related notes and
schedules thereto) fairly presents and will fairly present the financial
position of the entity or entities to which it relates as of its date, and each
of the statements of income and changes in shareholders' equity and cash flows
or equivalent statements in the USBN Financial Reports (including any related
notes and schedules thereto) fairly presents and will fairly present the results
of operations, changes in shareholders, equity and changes in cash flows, as the
case may be, of the entity or entities to which it relates for the periods set
forth therein, in each case in accordance with GAAP, except as may be noted
therein, subject to normal and recurring year-end audit adjustments in the case
of unaudited statements.

                (H) NO EVENTS. Except as Previously Disclosed on Schedule
4.2(H), since December 31, 1997, no event has occurred which is reasonably
likely to have a Material Adverse Effect on it.

                (I) LITIGATION; REGULATORY ACTION. Except as Previously
Disclosed in Schedule 4.2(I) no litigation, proceeding or controversy before any
court or governmental agency is pending that, individually or in the aggregate,
is reasonably likely to have a Material Adverse Effect on USBN or its
Subsidiaries or that alleges claims under any fair lending law or other law
relating to discrimination, including the Equal Credit Opportunity Act, the Fair
Housing Act, the Community Reinvestment Act and the Home Mortgage Disclosure
Act, and, to the best of its knowledge, no such litigation, proceeding or
controversy has been threatened; and except as Previously Disclosed in Schedule
4.2(I), neither USBN nor any of its Subsidiaries or any of its or their material
properties or their officers, directors or controlling 



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persons is a party to or is subject to any order, decree, agreement, memorandum
of understanding or similar arrangement with, or a commitment letter or similar
submission to, any Regulatory Authority, and neither USBN nor any of its
Subsidiaries has been advised by any of such Regulatory Authorities that such
authority is contemplating issuing or requesting (or is considering the
appropriateness of issuing or requesting) any such order, decree, agreement,
memorandum or understanding, commitment letter or similar submission.

                (J) REPORTS. Since January 1, 1996, each of USBN and its
Subsidiaries has filed all reports and statements, together with any amendments
required to be made with respect thereto, that it was required to file with (1)
the FDIC, (2) the Department, (3) the Federal Reserve Board, and (4) any other
Regulatory Authorities having jurisdiction with respect to USBN and its
Subsidiaries. As of their respective dates (and without giving effect to any
amendments or modifications filed after the date of this Plan with respect to
reports and documents filed before the date of this Plan), each of such reports
and documents, including the financial statements, exhibits and schedules
thereto, complied in all material respects with all of the statutes, rules and
regulations enforced or promulgated by the Regulatory Authority with which they
were filed and did not contain any untrue statement of a material fact or omit
to state any material fact necessary in order to make the statements made
therein, in light of the circumstances under which they were made, not
misleading.

                (K) ACCURACY OF INFORMATION. The statements with respect to USBN
and its Subsidiaries contained in this Plan, the Schedules and any other written
documents executed and delivered by or on behalf of USBN or any other Party
pursuant to the terms of this Plan are true and correct in all material
respects, and such statements and documents do not omit any material fact
necessary to make the statements contained therein, in light of the
circumstances under which they were made, not misleading.

                (L) DERIVATIVES CONTRACTS. None of USBN or its Subsidiaries is a
party to or has agreed to enter into a Derivatives Contract or owns securities
that are referred to as "structured notes" except for those Derivatives
Contracts and structured notes Previously Disclosed in Schedule 4.2(L). Schedule
4.2(L) includes a list of any assets of USBN or its Subsidiaries that are
pledged as security for each such Derivatives Contract.

                (M) ABSENCE OF UNDISCLOSED LIABILITIES. Neither USBN nor any of
its Subsidiaries has any obligation or liability (contingent or otherwise) that,
individually or in the aggregate, is reasonably likely to have a Material
Adverse Effect on it, except (1) as reflected the USBN Financial Reports prior
to the date of this Plan, and (2) for commitments and obligations made, or
liabilities incurred, in the ordinary course of business consistent with past
practice since December 31, 1997. Since December 31, 1997, neither USBN nor any
of its Subsidiaries has incurred or paid any obligation or liability (including
any obligation or liability incurred in connection with any acquisitions in
which any form of direct financial assistance of the federal government or any
agency thereof has been provided to any Subsidiary) that, individually or in the
aggregate, is reasonably likely to have a Material Adverse Effect on it.

                                  V. COVENANTS

        Each of Bancwest and Bank of the West hereby covenants to USBN, and USBN
hereby covenants to Bancwest and Bank of the West, that:

        5.1 BEST EFFORTS. Subject to the terms and conditions of this Plan and,
in the case of Bancwest and Bank of the West, to the exercise by their
respective Boards of Directors of such Boards' fiduciary duties, each party
shall use its best efforts in good faith to take, or cause to be taken, all
actions, and to do, or cause to be done, all things necessary, proper or
desirable, or advisable under applicable laws, so as to permit consummation of
the Merger by January 31, 1999, and to otherwise enable consummation of the
transactions contemplated by this Plan and the Stock Option Agreement, and shall
cooperate fully with 



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the other Parties to that end (it being understood that any amendments to the
Registration Statement or a resolicitation of proxies as a consequence of a USBN
Transaction shall not violate this covenant).

        5.2 THE PROXY. In the case of Bancwest: it shall promptly assist USBN in
the preparation of a joint proxy statement (the "Proxy Statement") to be mailed
to the holders of Bancwest Common Stock and USBN Common Stock in connection with
the transactions contemplated by this Plan and to be filed by USBN in a
registration statement (the "Registration Statement") with the SEC as provided
in Section 5.7, which shall conform to all applicable legal requirements.
Bancwest shall call a meeting (the "Bancwest Meeting") of the holders of
Bancwest Common Stock to be held as soon as practicable for purposes of voting
upon the transactions contemplated by this Plan and Bancwest shall use its best
efforts to solicit and obtain votes of the holders of Bancwest Common Stock in
favor of the transactions contemplated by this Plan and, subject to the exercise
of its fiduciary duties, the Board of Directors of Bancwest shall recommend
approval of such transactions by such holders. USBN shall call a meeting (the
"USBN Meeting") of the holders of USBN Common Stock to be held as soon as
practicable for purposes of voting upon the transactions contemplated by this
Plan and USBN shall use its best efforts to solicit and obtain votes of the
holders of USBN Common Stock in favor of the transactions contemplated by this
Plan and, subject to the exercise of its fiduciary duties, the Board of
Directors of USBN shall recommend approval of such transactions by such holders.

        5.3 REGISTRATION STATEMENT COMPLIANCE WITH SECURITIES LAWS. When the
Registration Statement or any post-effective amendment or supplement thereto
shall become effective, and at all times subsequent to such effectiveness, up to
and including the date of the Bancwest Meeting and the USBN Meeting
(collectively, the "Meetings"), such Registration Statement, and all amendments
or supplements thereto, with respect to all information set forth therein
furnished or to be furnished by or on behalf of Bancwest relating to Bancwest or
its Subsidiaries and by or on behalf of USBN relating to USBN or its
Subsidiaries, (A) will comply in all material respects with the provisions of
the Securities Act and any other applicable statutory or regulatory
requirements, and (B) will not contain any untrue statement of a material fact
or omit to state a material fact required to be stated therein or necessary to
make the statements contained therein not misleading; provided, however, in no
event shall any Party be liable for any untrue statement of a material fact or
omission to state a material fact in the Registration Statement made in reliance
upon, and in conformity with, written information concerning another Party
furnished by or on behalf of such other Party specifically for use in the
Registration Statement.

        5.4 REGISTRATION STATEMENT EFFECTIVENESS. USBN will advise Bancwest,
promptly after USBN receives notice thereof, of the time when the Registration
Statement has become effective or any supplement or amendment has been filed, of
the issuance of any stop order or the suspension of the qualification of the
USBN Common Stock for offering or sale in any jurisdiction, of the initiation or
threat of any proceeding for any such purpose, or of any request by the SEC for
the amendment or supplement of the Registration Statement or for additional
information.

        5.5 PRESS RELEASES. Bancwest and Bank of the West will not, without the
prior approval of USBN, and USBN will not, without the prior approval of
Bancwest, issue any press release or written statement for general circulation
relating to the transactions contemplated by this Plan, except as otherwise
required by law.

        5.6 ACCESS; INFORMATION.

                (A) Upon reasonable notice, Bancwest and Bank of the West shall
afford USBN and its officers, employees, counsel, accountants and other
authorized representatives, access, during normal business hours throughout the
period up to the Effective Date, to all of the properties, books, contracts,
commitments and records of Bancwest and its Subsidiaries and, during such
period, Bancwest and Bank of the West shall furnish promptly (and cause its
accountants and other agents to furnish promptly) to USBN 



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(1) a copy of each material report, schedule and other document filed by
Bancwest and its Subsidiaries with any Regulatory Authority, (2) such
representations and certifications as are necessary for purposes of the pooling
letter described in Section 6.1(H), and (3) all other information concerning the
business, properties and personnel of Bancwest and its Subsidiaries as USBN may
reasonably request, provided that no investigation pursuant to this Section 5.6
shall affect or be deemed to modify or waive any representation or warranty made
by Bancwest or Bank of the West in this Plan or the conditions to the
obligations of Bancwest and Bank of the West to consummate the transactions
contemplated by this Plan; and

                (B) USBN will not use any information obtained pursuant to this
Section 5.6 for any purpose unrelated to the consummation of the transactions
contemplated by this Plan and, if this Plan is terminated, will hold all
information and documents obtained pursuant to this paragraph in confidence (as
provided in Section 8.6) unless and until such time as such information or
documents become publicly available other than by reason of any action or
failure to act by USBN or as it is advised by counsel that any such information
or document is required by law or applicable stock exchange rule to be
disclosed, and in the event of the termination of this Plan, USBN will, upon
request by Bancwest, deliver to Bancwest all documents so obtained by USBN or
destroy such documents and, in the case of destruction, will certify such fact
to Bancwest.

        5.7 REGISTRATION STATEMENT PREPARATION; REGULATORY APPLICATIONS
PREPARATION. USBN shall, as promptly as practicable following the date of this
Plan, prepare and file the Registration Statement with the SEC with respect to
the shares of USBN Common Stock to be issued to the holders of Bancwest Common
Stock pursuant to this Plan, and USBN shall use its best efforts to cause the
Registration Statement to be declared effective as soon as practicable after the
filing thereof. USBN shall, as promptly as practicable following the date of
this Plan, prepare and file all necessary notices or applications with
Regulatory Authorities having jurisdiction with respect to the transactions
contemplated by this Plan.

        5.8 BLUE-SKY FILINGS. USBN shall use its best efforts to obtain, prior
to the effective date of the Registration Statement, any necessary state
securities laws or "blue sky" permits and approvals, provided that USBN shall
not be required by virtue thereof to submit to general jurisdiction in any
state.

        5.9 AFFILIATE AGREEMENTS. Bancwest will use its best efforts to induce
each person who may be deemed to be an "affiliate" of Bancwest for purposes of
Rule 145 under the Securities Act, to execute and deliver to USBN on or before
the mailing of the Proxy Statement for the Bancwest Meeting, an agreement in the
form attached hereto as Exhibit E restricting the disposition of such
affiliate's shares of Bancwest Common Stock, and, in the case of "affiliates" of
Bancwest, the shares of USBN Common Stock to be received by such person in
exchange for such person's shares of Bancwest Common Stock. USBN agrees to use
its best efforts to maintain the availability of Rule 145 for use by such
"affiliates".

        5.10 CERTAIN POLICIES OF BANCWEST AND BANK OF THE WEST. Bancwest and
Bank of the West, each shall, at USBN's request, modify and change its loan,
litigation and other reserve and real estate valuation policies and practices
(including loan classifications and levels of reserves), and generally conform
its operating, lending and compliance policies and procedures, immediately prior
to the Effective Date so as to be consistent on a mutually satisfactory basis
with those of USBN and GAAP; provided, however, that prior to any such
modification or change, USBN shall certify that the conditions to the obligation
of USBN under Section 6.1 and 6.2 to consummate the transactions contemplated by
this Plan have been satisfied or waived. Bancwest's and Bank of the West's
representations, warranties, covenants and conditions contained in this Plan
shall not be deemed to be untrue, breached or unsatisfied in any respect for any
purpose as a consequence of any modifications or changes undertaken pursuant to
this Section 5.10.



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        5.11 STATE TAKEOVER LAW. Bancwest shall not take any action that would
cause the transactions contemplated by this Plan to be subject to any applicable
state takeover statute, and Bancwest shall take all necessary steps to exempt
(or ensure the continued exemption of) the transactions contemplated by this
Plan and the Stock Option Agreement from, or, if necessary, challenge the
validity or applicability of, any applicable state takeover law.

        5.12 NO RIGHTS TRIGGERED. Except for those consents of Third Parties
Previously Disclosed on Schedule 4.1(G), Bancwest shall take all necessary steps
to ensure that the entering into of this Plan and the Stock Option Agreement and
the consummation of the transactions contemplated by this Plan and the Stock
Option Agreement (including the Merger) and any other action or combination of
actions, or any other transactions contemplated by this Plan, do not and will
not (A) result in the grant of any rights to any Person under the articles of
incorporation or bylaws of Bancwest or under any agreement to which Bancwest or
any of its Subsidiaries is a party, or (B) restrict or impair in any way the
ability of USBN to exercise the rights granted under this Plan or the Stock
Option Agreement.

        5.13 SHARES LISTED. USBN shall use its best efforts to cause to be
listed, prior to the Effective Date, on the NASDAQ National Market upon official
notice of issuance the shares of USBN Common Stock to be issued to the holders
of Bancwest Common Stock.

        5.14 REGULATORY APPLICATIONS. USBN shall (A) promptly prepare and submit
applications to the appropriate Regulatory Authorities for approval of the
Merger, and (B) promptly make all other appropriate filings to secure all other
approvals, consents and rulings that are necessary for the consummation of the
Merger by USBN.

        5.15 REGULATORY DIVESTITURES. In the case of Bancwest: No later than the
Effective Date, Bancwest shall cease engaging in such activities as USBN shall
advise Bancwest in writing are not permitted to be engaged in by USBN under
applicable law following the Effective Date and, to the extent required by any
Regulatory Authority as a condition of approval of the transactions contemplated
by this Plan, Bancwest shall divest any Subsidiary engaged in activities or
holding assets that are impermissible for USBN, on terms and conditions agreed
to by USBN; provided, however, that prior to taking such action, USBN shall
certify that the conditions to the obligations of USBN under Sections 6.1 and
6.2 to consummate the transactions contemplated by this Plan, other than the
condition set forth in Section 6.2(G) (which shall be adjusted to the extent
that assets are divested at less than book value), have been satisfied or
waived.

        5.16 CURRENT INFORMATION.

                (A) During the period from the date of this Plan to the
Effective Date, each of Bancwest and USBN shall, and shall cause its
representatives to, confer on a regular and frequent basis with representatives
of the other.

                (B) Each of Bancwest and USBN shall promptly notify the other of
(1) any material change in the business or operations of it or its Subsidiaries,
(2) any material complaints, investigations or hearings (or communications
indicating that the same may be contemplated) of any Regulatory Authority
relating to it or its Subsidiaries, (3) the initiation or threat of material
litigation involving or relating to it or its Subsidiaries, or (4) any event or
condition that might reasonably be expected to cause any of its representations
or warranties set forth in this Plan not to be true and correct in all material
respects as of the Effective Date or prevent it or its Subsidiaries from
fulfilling its or their obligations under this Plan.



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<PAGE>   125


        5.17 INDEMNIFICATION.

                (A) For a period of four years from and after the Effective
Date, USBN will indemnify, defend and hold harmless the present and former
directors and officers of Bancwest and the Bank (each, an "Indemnified Party")
against all costs or expenses (including reasonable attorneys' fees), judgments,
fines, losses, claims, damages or liabilities incurred in connection with any
claim, action, suit, proceeding or investigation, whether civil, criminal,
administrative or investigative, and arising out of matters existing or
occurring at or prior to the Effective Date (including the transactions
contemplated by this Plan), whether asserted or claimed prior to, at or after
the Effective Date, to the fullest extent that Bancwest and/or the Bank would
have been permitted under Washington and federal law and their respective
articles of incorporation or bylaws in effect on the date of this Plan to
indemnify such person (and USBN will also advance expenses as incurred to the
fullest extent permitted under applicable law so long as the person to whom
expenses are advanced provides an undertaking to repay such advances within a
reasonable period of time if it is ultimately determined that applicable law
does not allow for such indemnification).

                (B) Any Indemnified Party wishing to claim indemnification under
paragraph (A) of this Section 5.17, upon learning of such claim, action, suit,
proceeding or investigation, will promptly notify USBN of the same, provided,
however, that the failure so to notify will not affect the obligations of USBN
under paragraph (A) of this Section 5.17 (unless such failure materially and
adversely increases USBN's liability under such paragraph (A)). In the event of
any such claim, action, suit, proceeding or investigation (whether arising
before or after the Effective Date), (1) USBN will have the right to assume the
defense and USBN will pay all reasonable fees and expenses of such counsel for
the Indemnified Parties promptly as statements for payment are received;
provided, however, that USBN will be obligated pursuant to this paragraph (B) to
pay for only one firm of counsel for all Indemnified Parties in any jurisdiction
for any single action, suit or proceeding, (2) the Indemnified Parties will
cooperate in the defense of any such matter, and (3) USBN will not be liable for
any settlement effected without its prior written consent.

                (C) If USBN or any of its successors or assigns will consolidate
with or merge into any other entity and will not be the continuing or surviving
entity of such consolidation or merger or will transfer all or substantially all
of its assets to any entity, then and in each case, proper provision will be
made so that the successors and assigns of USBN will assume the obligations set
forth in this Section 5.17.

                (D) USBN will pay all expenses, including attorneys' fees, that
may be incurred by any Indemnified Party in enforcing the indemnity and other
obligations provided for in this Section 5.17. The rights of each Indemnified
Party under this Section 5.17 will be in addition to any other rights such
Indemnified Party may have under the articles of association or bylaws of
Bancwest or the Bank or under applicable Washington and federal law.

        5.18 BOARDS OF DIRECTORS OF USBN AND BANK OF THE WEST.

                (A) USBN shall, prior to the Effective Date, make such
amendments to its Bylaws as may be necessary to facilitate the appointment of
three members of the Board of Directors of Bancwest, selected by the Board of
Bancwest and approved by the Board of USBN (the "Bancwest Directors"), to serve
on USBN's Board of Directors following the Effective Date. Immediately after the
Effective Date, USBN shall appoint the Bancwest Directors to the Board of
Directors of USBN to serve in such capacity until such time as their successors
are elected and qualified.

                (B) Immediately after the Effective Date, the Board of Directors
of Bank of the West shall be comprised of the directors of Bank of the West
immediately prior to the Effective Date plus two additional directors designated
by USBN, all of whom shall serve as directors until such time as their
successors are elected and qualified.



                                     A - 25


<PAGE>   126


        5.19 ACQUISITION PROPOSALS. Bancwest agrees that neither it nor any of
its Subsidiaries shall, and Bancwest shall direct and use its best efforts to
cause its directors, officers, employees, agents and representatives (including,
without limitation, any investment banker, attorney or accountant retained by it
or any of its Subsidiaries) not to, initiate, solicit, encourage or take any
other action to facilitate any inquiries or the making of any proposal or offer
(including, without limitation, any proposal or offer to stockholders of
Bancwest) with respect to a merger, consolidation or similar transaction
involving, or any purchase of all or any significant portion of the assets or
equity securities of, Bancwest or any of its Subsidiaries (any such proposal or
offer being hereinafter referred to as an "Acquisition Proposal") or, except to
the extent legally required for the discharge by the board of directors of its
fiduciary duties as advised in writing by such board's counsel, engage in any
negotiations concerning, or provide any confidential information or data to any
Person relating to, an Acquisition Proposal, or otherwise facilitate any effort
or attempt to make or implement an Acquisition Proposal. Bancwest will
immediately cease and cause to be terminated any existing activities,
discussions or negotiations with any parties conducted heretofore with respect
to any of the foregoing. Bancwest will take the necessary steps to inform the
appropriate individuals or entities referred to in the first sentence hereof of
the obligations undertaken in this Section 5.19 of this Plan. Bancwest will
notify USBN immediately if any such inquiries or proposals are received by, any
such information is requested from, or any such negotiations are sought to be
initiated or continued with Bancwest.

        5.20 POST-MERGER ACTIONS. Following the Merger, neither USBN nor any of
its affiliates shall take any action that will adversely affect the federal
income tax treatment of the Merger to the shareholders of Bancwest, including
failing to continue at least one historic business line of Bancwest or to use at
least a significant portion of Bancwest's historic assets in a business, in each
case within the meaning of Treas. Reg. Section 1.368-1(d).

                  VI. CONDITIONS TO CONSUMMATION OF THE MERGER

        6.1 CONDITIONS TO EACH PARTY'S OBLIGATIONS. The respective obligations
of each Party to consummate the transactions contemplated by this Plan are
subject to the written waiver by such Party or the fulfillment on or prior to
the Effective Date of each of the following conditions:

                (A) SHAREHOLDER VOTES. This Plan shall have been duly approved
by the requisite vote of the shareholders of Bancwest and USBN under applicable
law and the articles of incorporation and bylaws of Bancwest and USBN,
respectively.

                (B) REGULATORY APPROVALS. The Parties shall have procured all
necessary regulatory consents and approvals by the appropriate Regulatory
Authorities, and any waiting periods relating thereto shall have expired;
provided, however, that no such approval or consent shall have imposed any
condition or requirement not normally imposed in such transactions that, in the
opinion of USBN, would deprive USBN of the material economic or business
benefits of the transactions contemplated by this Plan.

                (C) NO INJUNCTION. There shall not be in effect any order,
decree or injunction of any court or agency of competent jurisdiction that
enjoins or prohibits consummation of any of the transactions contemplated by
this Plan.

                (D) EFFECTIVE REGISTRATION STATEMENT. The Registration Statement
shall have become effective and no stop order suspending the effectiveness of
the Registration Statement shall have been issued and no proceedings for that
purpose shall have been initiated or threatened by the SEC or any other
Regulatory Authority.



                                     A - 26

<PAGE>   127


                (E) BLUE-SKY PERMITS. USBN shall have received all state
securities laws and "blue sky" permits necessary to consummate the Merger.

                (F) TAX OPINION. USBN and Bancwest shall have received an
opinion from Graham & Dunn, P.C. to the effect that (1) the Merger constitutes a
reorganization under Section 368 of the Code, and (2) no gain or loss will be
recognized by shareholders of Bancwest who receive shares of USBN Common Stock
in exchange for their shares of Bancwest Common Stock, except that gain or loss
may be recognized as to cash received in lieu of fractional share interests,
and, in rendering their opinion, Graham & Dunn, P.C. may require and rely upon
representations contained in certificates of officers of USBN, Bancwest and
others.

                (G) NASDAQ LISTING. The shares of USBN Common Stock to be issued
pursuant to this Plan shall have been approved for listing on the NASDAQ
National Market subject only to official notice of issuance.

                (H) POOLING LETTER. USBN shall have received a letter from Moss
Adams, LLP, dated as of the date of this Plan and as of the Effective Date, in
form and substance acceptable to USBN, to the effect that the Merger will
qualify for pooling of interests accounting treatment.

        6.2 CONDITIONS TO OBLIGATIONS OF USBN. The obligations of USBN to
consummate the transactions contemplated by this Plan also are subject to the
written waiver by USBN or the fulfillment on or prior to the Effective Date of
each of the following conditions:

                (A) LEGAL OPINION. USBN shall have received an opinion, dated
the Effective Date, of Keller Rohrback, L.L.P., counsel for Bancwest and Bank of
the West, in the form of Exhibit F.

                (B) OFFICERS' CERTIFICATE. (1) Each of the representations and
warranties contained in this Plan of Bancwest and Bank of the West shall be true
and correct in all material respects as of the date of this Plan and upon the
Effective Date with the same effect as though all such representations and
warranties had been made on the Effective Date, except for (a) any such
representations and warranties that specifically relate to an earlier date,
which shall be true and correct as of such earlier date and except as otherwise
provided in Section 5.10 and (b) any such representations and warranties that
are qualified by reference to "Material Adverse Effect", which representations
and warranties shall be true in all respects, and (2) each and all of the
agreements and covenants of Bancwest and Bank of the West to be performed and
complied with pursuant to this Plan on or prior to the Effective Date shall have
been duly performed and complied with in all material respects, and USBN shall
have received a certificate signed by the chief executive officers, chief
financial officer/chief lending officer of Bancwest and Bank of the West dated
the Effective Date, to such effect.

                (C) RECEIPT OF AFFILIATE AGREEMENTS. USBN shall have received
from each affiliate of Bancwest the agreement referred to in Section 5.9.

                (D) ADVERSE CHANGE. During the period from December 31, 1997 to
the Effective Date, there shall not have been any material adverse change in the
financial position or results of operations of Bancwest or Bank of the West, nor
shall Bancwest or Bank of the West have sustained any loss or damage to its
properties, whether or not insured, nor shall there have been any other event,
occurrence or circumstance which would have a Material Adverse Effect upon its
ability to conduct its business; and USBN shall have received a certificate
dated the Effective Date signed by the Chief Executive Officers of Bancwest and
Bank of the West to such effect.

                (E) DISSENTERS' RIGHTS. The number of shares of Bancwest Common
Stock for which cash is to be paid because dissenters' rights of appraisal under
the Appraisal Laws shall have been 



                                     A - 27

<PAGE>   128


effectively preserved as of the Effective Date or because of the payment of cash
in lieu of fractional shares of USBN Common Stock shall not exceed in the
aggregate 10% of the outstanding shares of Bancwest Common Stock.

                (F) CAPITAL. Bancwest's Capital shall not be less than $11.9
million (not including capital contributions upon exercise of outstanding
Bancwest Options) on the Effective Date.

                (G) ALLOWANCE FOR LOAN AND LEASE LOSSES. Bank of the West's
allowance for possible loan and lease losses shall not be less than 1.00% of
Bank of the West's total outstanding loans and leases and will be adequate under
GAAP (based on USBN's reasonable analysis).

                (H) EMPLOYMENT CONTRACT. The Employment Agreement attached as
Exhibit D shall have been duly executed and delivered by all parties to such
Employment Agreement.

                (I) AUDIT. Bancwest shall have delivered to USBN the audited
consolidated balance sheet of Bancwest as at December 31, 1997, and the related
audited consolidated statements of income, changes in stockholders' equity, and
cash flow for the fiscal year then ended, together with the unqualified report
on such financial statements of Moss Adams L.L.P., independent certified public
accountants, and such financial statements shall fairly present the consolidated
financial condition and the results of operations, changes in stockholders'
equity, and cash flow of Bancwest as at the date of and for the period referred
to in such financial statements, all in accordance with GAAP and reflecting the
consistent application of such accounting principles throughout the period
involved.

                (J) FAIRNESS OPINION. USBN shall have received, immediately
prior to the mailing of the Proxy Statement to Bancwest's shareholders, an
opinion of Pacific Crest Securities to the effect that the financial terms of
the Merger are fair from a financial point of view to USBN's shareholders.

        6.3 CONDITIONS TO OBLIGATIONS OF BANCWEST AND BANK OF THE WEST. The
obligations of Bancwest and Bank of the West to consummate the transactions
contemplated by this Plan also are subject to the written waiver by Bancwest and
Bank of the West or the fulfillment on or prior to the Effective Date of each of
the following conditions:

                (A) LEGAL OPINION. Bancwest and Bank of the West shall have
received an opinion, dated the Effective Date, of Graham & Dunn, P.C., counsel
for USBN, in the form of Exhibit G.

                (B) OFFICER'S CERTIFICATE. (1) Each of the representations and
warranties of USBN contained in this Plan shall be true and correct in all
material respects as of the date of this Plan and upon the Effective Date with
the same effect as though all such representations and warranties had been made
on the Effective Date, except for (a) any such representations and warranties
that specifically relate to an earlier date, which shall be true and correct as
of such earlier date and (b) any such representations and warranties that are
qualified by reference to "Material Adverse Effect", which representations and
warranties shall be true in all respects, and (2) each and all of the agreements
and covenants of USBN to be performed and complied with pursuant to this Plan on
or prior to the Effective Date shall have been duly performed and complied with
in all material respects, and Bancwest shall have received a certificate signed
by an executive officer of USBN dated the Effective Date, to such effect.

                (C) ADVERSE CHANGE. During the period from December 31, 1997 to
the Effective Date, there shall not have been any material adverse change in the
financial position or results of operations of USBN nor shall USBN have
sustained any loss or damage to its properties, whether or not insured, that
materially affects its ability to conduct its business; and Bancwest shall have
received a certificate dated the Effective Date signed by the Chief Executive
Officer of USBN to such effect.



                                     A - 28

<PAGE>   129


                (D) FAIRNESS OPINION. Bancwest shall have received, immediately
prior to the mailing of the Proxy Statement to Bancwest's shareholders, an
opinion of Columbia Financial Advisors, Inc., to the effect that the financial
terms of the Merger are fair from a financial point of view to Bancwest's
shareholders.

                                VII. TERMINATION

        7.1 EVENTS OF TERMINATION. This Plan may be terminated prior to the
Effective Date, either before or after receipt of required shareholder
approvals:

                (A) MUTUAL CONSENT. By the mutual consent of USBN and Bancwest,
if the Board of Directors of each so determines by vote of a majority of the
members of its entire board.

                (B) BREACH. By USBN or Bancwest, if its Board of Directors so
determines by vote of a majority of the members of its entire Board, in the
event of (A) a material breach by the other Party of any representation or
warranty contained herein, which breach cannot be or has not been cured within
30 days after the giving of written notice to the breaching Party of such
breach, or (B) a breach by the other party of any of the material covenants or
agreements contained, which breach cannot be or has not been cured within 30
days after the giving of written notice to the breaching Party of such breach.

                (C) DELAY. By USBN or Bancwest in the event the Merger is not
consummated by June 30, 1999, unless the failure of the consummation of the
transactions to occur shall be due to the failure of the Party seeking to
terminate this Merger Agreement to perform its obligations hereunder in a timely
manner; provided, however, that USBN may not terminate the Merger Agreement
pursuant to this Section 7.1(C), if such delay results solely from (a)
amendments to the Registration Statement or a resolicitation of proxies as a
consequence of a USBN Transaction, or any other acquisition or sale transaction,
or any offering of securities, in which USBN is involved, or (b) a change in the
method of acquisition pursuant to Section 2.7; and provided, further, that a
party may not terminate the Merger Agreement pursuant to this Section 7.1(C) if
it is in material breach of any of the provisions of the Merger Agreement.

                (D) NO SHAREHOLDER APPROVAL. By USBN or Bancwest, if its Board
of Directors so determines by a vote of a majority of the members of its entire
Board, in the event that the shareholder approvals contemplated by Section 6.1
are not obtained at the Meetings, including any adjournment or adjournments the
Meetings.

                (E) AVERAGE CLOSING PRICE BELOW $12.50. By Bancwest, on or
before the fifth day after the end of the trading period used to determine the
Average Closing Price, if the Average Closing Price, subject to adjustment as
provided in Section 2.5 hereof, is less than $12.50 and USBN, in its sole
discretion, does not elect by written notice to Bancwest prior to such fifth day
to increase the Exchange Ratio (as so increased, the "Adjusted Exchange Ratio")
so that the Average Closing Price multiplied by the Adjusted Exchange Ratio
equals the product of the Exchange Ratio multiplied by $12.50.

                (F) FIDUCIARY DUTIES. By Bancwest, if its Board of Directors,
after receiving advice of counsel, determines in its good faith that it is
required to do so in order to discharge its fiduciary duties, shall withdraw or
modify or resolve to withdraw or modify its recommendation that the shareholders
vote in favor of the Merger.

        7.2 CONSEQUENCES OF TERMINATION.

                (A) GENERAL CONSEQUENCES. Subject to Section 7.3 and Section
8.5, in the event of the termination or abandonment of this Plan pursuant to the
provisions of Section 7.1, this Plan


                                     A - 29

<PAGE>   130


shall become void and have no force or effect, without any liability on the part
of the Parties or any of their respective directors or officers or shareholders
with respect to this Plan.

                (B) ENFORCEMENT PROCEEDINGS. In any action or proceeding in
connection with the enforcement of this Plan, the prevailing party will be
entitled to reasonable attorneys' fees and expenses.

        7.3 TERMINATION FEE. The parties hereby acknowledge that, in negotiating
and executing this Plan and in taking the steps necessary or appropriate to
effect the transaction contemplated hereby, USBN and Bancwest have each incurred
and will incur direct and indirect monetary and other costs (including without
limitation attorneys' fees and costs of their respective employee and management
time) and will forego discussions with respect to other potential transactions.

                (A) To compensate USBN for such costs and to induce it to forego
initiating discussions regarding other transactions and as liquidated damages,
if (i) this Plan terminates because Bancwest does not use its best efforts to
consummate the transactions contemplated by this Plan in accordance with the
terms of this Plan (unless a condition set forth in Section 6.1 or Section 6.3
is not satisfied and such nonsatisfaction has not been the result of the failure
of Bancwest to use its best efforts to consummate this Plan in accordance with
the terms of this Plan), or (ii) Bancwest terminates this Plan for any reason
other than the grounds for termination set out in Section 7.1(A), 7.1(B), or
7.1(C), then Bancwest shall be obligated to pay USBN on demand (and in no event
more than three days after such demand) in immediately available funds $500,000.
It is further understood and agreed that the fee payable under this Section
shall be due and owing even though the event or condition which caused the fee
to be payable was the result (in part or in whole) of the directors of Bancwest
complying with their fiduciary duties.

                (B) To compensate Bancwest for such costs and to induce it to
forego initiating discussions regarding other transactions and as liquidated
damages, if (i) this Plan terminates because USBN does not use its best efforts
to consummate the transactions contemplated by this Plan in accordance with the
terms of this Plan (unless a condition set forth in Section 6.1 or 6.2 is not
satisfied and such nonsatisfaction has not been the result of the failure of
USBN to use its best efforts to consummate this Plan in accordance to the terms
of this Plan), or (ii) USBN terminates this Plan for any reason other than the
grounds for termination set out in Section 7.1(A), 7.1(B), or 7.1(C), then USBN
shall be obligated to pay Bancwest on demand (and in no event more than three
days after such demand) in immediately available funds $500,000.

                               VIII. OTHER MATTERS

        8.1 SURVIVAL. Only those agreements and covenants in this Plan that by
their express terms apply in whole or in part after the Effective Date shall
survive the Effective Date. All other representations, warranties, and covenants
shall be deemed only to be conditions of the Merger and shall not survive the
Effective Date. If the Merger is abandoned and this Plan is terminated, the
provisions of Article VII shall apply and the agreements of the Parties in
Sections 7.3, 8.5 and 8.6 shall survive such abandonment and termination.

        8.2 WAIVER; AMENDMENT. Prior to the Effective Date, any provision of
this Plan may be (A) waived in writing by the Party benefited by the provision,
or (B) amended or modified at any time (including the structure of the
transactions contemplated by this Plan) by an agreement in writing among the
Parties approved by their respective Boards of Directors and executed in the
same manner as this Plan, except that, after the vote by the shareholders of
Bancwest and USBN, the consideration to be received by the shareholders of
Bancwest for each share of Bancwest Common Stock shall not thereby be altered.
Nothing contained in this Section 8.2 is intended to modify USBN's rights
pursuant to Section 2.7.



                                     A - 30

<PAGE>   131


        8.3 COUNTERPARTS. This Plan may be executed in one or more facsimile
counterparts, each of which shall be deemed to constitute an original. This Plan
shall become effective when one counterpart has been signed by each Party.

        8.4 GOVERNING LAW. This Plan shall be governed by, and interpreted in
accordance with, the laws of the State of Washington, except as federal law may
be applicable.

        8.5 EXPENSES. Each Party will bear all expenses incurred by it in
connection with this Plan and the transactions contemplated by this Plan, except
printing expenses which shall be shared equally between Bancwest and USBN. In
the event of termination of this Plan pursuant to Section 7.1(A) or 7.1(D) or if
Bancwest does not consummate the Merger because one or more of the conditions
set forth in Section 6.3(A), 6.3(B) or 6.3(C) has not been satisfied, Bancwest
and USBN will share equally the expenses incurred by Bancwest in obtaining
audited financial statements for the purposes of the Merger.

        8.6 CONFIDENTIALITY. Except as otherwise provided in Section 5.6(B),
each of the Parties and their respective agents, attorneys and accountants will
maintain the confidentiality of all information provided in connection herewith
which has not been publicly disclosed.

        8.7 NOTICES. All notices, requests and other communications hereunder to
a "Party" shall be in writing and shall be deemed to have been duly given when
delivered by hand, telegram, certified or registered mail, overnight courier,
telecopy or telex (confirmed in writing) to such Party at its address set forth
below or such other address as such Party may specify by notice to the Parties.

If to USBN, to:

                                  United Security Bancorporation
                                  N. 9506 Newport Hwy
                                  Spokane, WA 99218
                                  Attn: William D. Dashiell and Richard C. Emery

                      Copies to:

                                  Stephen M. Klein
                                  Graham & Dunn, P.C.
                                  1420 Fifth Avenue, 33rd Floor
                                  Seattle, WA 98101


If to Bancwest or Bank of the West, to:

                                  BANCWEST FINANCIAL CORPORATION
                                  P.O. Box 1597
                                  Walla Walla, WA 99362
                                  Attn:  Wes Colley

                      Copies to:

                                  Glen P. Garrison
                                  Keller Rohrback, L.L.P.
                                  Suite 3200
                                  1201 Third Avenue
                                  Seattle, WA 98101-3052



                                     A - 31

<PAGE>   132


        8.8 ENTIRE UNDERSTANDING; NO THIRD PARTY BENEFICIARIES. This Plan and
the Stock Option Agreement represents the entire understanding of the Parties
with reference to transactions contemplated by this Plan and the Stock Option
Agreement and supersede any and all other oral or written agreements previously
made. Nothing in this Plan, expressed or implied, is intended to confer upon any
Person, other than the Parties or their respective successors, any rights,
remedies, obligations or liabilities under or by reason of this Plan or the
Stock Option Agreement.

        8.9 BENEFIT PLANS. From and after the Effective Date, employees of
Bancwest and its Subsidiaries shall be entitled to participate in the Employee
Stock Ownership Plan, employee benefit and similar plans (including stock
option, bonus or other incentive plans) of the Continuing Corporation and its
Subsidiaries so that employees of Bancwest and its Subsidiaries shall, following
the Merger, receive total compensation substantially comparable to that received
immediately prior to the Merger. For the purpose of determining eligibility to
participate in such plans and the vesting of benefits under any USBN plans (but
not for the accrual of benefits), USBN shall give effect to years of service
with Bancwest or Bancwest's Subsidiaries, as the case may be, as if such service
were with USBN or its Subsidiaries. Employees of Bancwest and its Subsidiaries
will be entitled to carry over unused vacation days and sick leave accrued as of
the Effective Date. Upon consummation of the Merger, all employees of Bancwest
and its Subsidiaries shall be deemed to be at-will employees of USBN and its
Subsidiaries, except for Wes Colley, who is party to the Employment Agreement,
and any other employees who enter into written employment agreements with USBN
or its Subsidiaries.

8.10 HEADINGS. The headings contained in this Plan are for reference purposes
only and are not part of this Plan.

        IN WITNESS WHEREOF, the Parties have caused this instrument to be
executed in counterparts by their duly authorized officers, all as of the day
and year first above written.

UNITED SECURITY FINANCIAL CORPORATION



By: /s/ William C. Dashiell
   --------------------------------
      William C. Dashiell
      Its Chairman


By: /s/ Richard C. Emery
   --------------------------------
      Richard C. Emery
      Its President and Chief Executive Officer


BANCWEST BANCORPORATION



By: /s/ Wes Colley
   --------------------------------
      Wes Colley
      Its President and Chairman


                                     A - 32


<PAGE>   133


BANK OF THE WEST



By: /s/ Wes Colley
   --------------------------------
      Wes Colley
      Its President and Chief Executive Officer




                                     A - 33
<PAGE>   134

                                                                      APPENDIX B

November 10, 1998


The Board of Directors
United Security Bancorporation
North 9506 Newport Highway
Spokane, Washington 99218

Members of the Board:

You have asked us to advise you with respect to the fairness to shareholders of
United Security Bancorporation (the "Company"), from a financial point of view,
of the purchase of all of the outstanding shares of Bancwest Financial Corp.
("Bancwest") in exchange for shares of the Company ("Acquisition"), pursuant to
the proposed Agreement and Plan of Reorganization ("Agreement"), dated as of
November 10, 1998 between the Company and Bancwest.

Pacific Crest Securities is an investment banking firm that performs financial
advisory services. We have acted as financial advisor to the Board of Directors
in connection with the Acquisition and will receive a fee for our services, a
portion of which is contingent upon delivery of the Opinion and inclusion in
materials to shareholders of the Company. We have in the past provided
investment banking services to the Company and have received customary fees for
the rendering of such services. In addition, in the ordinary course of our
business, we have actively traded the common stock of the Company for our own
account and for the accounts of customers and, accordingly, may at any time hold
a long or a short position in such securities.

In arriving at our opinion, we have reviewed certain publicly available business
and financial information relating to the Company and Bancwest. We have reviewed
certain other information, including financial forecasts, provided to us by the
Company and Bancwest, and have spoken with the Bancwest's management to discuss
the business and prospects of Bancwest.

We have also considered certain financial data of the Company and Bancwest, and
compared the data with similar data for publicly held banks or bank holding
companies. Additionally, we have considered the financial terms of certain other
business combinations in the commercial banking industry that have recently been
effected. We have considered certain pro forma combined financial information of
the Company and Bancwest. We also considered such other information, financial
studies, analyses and investigations and financial, economic and market criteria
which we deemed relevant.



                                      B-1


<PAGE>   135


In connection with our review, we have not independently verified any of the
foregoing information and have relied on its being complete and accurate in all
material respects. With respect to the financial forecasts, we have assumed that
they have been reasonably prepared on bases reflecting the best currently
available estimates and judgments of the Company's and Bancwest's management as
to the future financial performance of the Company and Bancwest. In addition, we
have not made an independent evaluation or appraisal of any of the assets of the
Company or Bancwest nor have we examined any individual loan files or been
furnished with any such appraisals.

We were retained by the Board of Directors of the Company and our opinion as
expressed herein is limited to the fairness, from a financial point of view to
the common stockholders of the Company, of the Acquisition and does not address
the Company's underlying business decision to proceed with the Acquisition. Our
opinion is necessarily based on conditions as they exist and can be evaluated on
the date hereof and the information made available to us through the date
hereof. This letter does not constitute a recommendation to the Board of
Directors or to any common stockholder of the Company with respect to any
approval of Acquisition.

We agree to the inclusion of this opinion letter in the Proxy
Statement/Prospectus relating to the Acquisition. The opinion may not, however,
be summarized, excerpted from or otherwise publicly referred to without our
prior written consent.

Based upon and subject to the foregoing, it is our opinion that, as of the date
of this letter, the consideration to be paid by the Company to the holders of
Bancwest common stock is fair, from a financial point of view, to the holders of
the Company's common stock.

Very truly yours,

PACIFIC CREST SECURITIES INC.



By: /s/ Albert V. Glowasky
   --------------------------------------
   Albert V. Glowasky
   Senior Vice President


                                      B-2



<PAGE>   136

                                                                      APPENDIX C






                                December , 1998



Board of Directors
Bancwest Financial Corporation
30 West Main Street
Walla Walla, WA  99362

Members of the Board:

        You have requested our opinion as to the fairness, from a financial
point of view, to the shareholders of Bancwest Financial Corporation ("BFC") of
the consideration to be received by such shareholders pursuant to the terms of
the Merger Agreement and Plan of Merger, dated November 10, 1998, (the
"Agreement") between BFC and United Security Bancorporation ("USBN").

        In connection with the proposed merger transaction (the "Merger")
whereby BFC will merge into USBN, each issued and outstanding share and option
of BFC common stock (along with its associated rights) at the effective time of
the Merger (other than (i) shares of holders of which are exercising appraisal
rights pursuant to applicable law and (ii) shares held directly by or indirectly
by the Bank, its parent company or any subsidiary thereof other than shares held
in a fiduciary capacity or in satisfaction of a debt previously contracted)
shall be converted into the right to receive 4.7038 of USBN shares and an
additional number of shares based on the net income earned by BFC between
January 1, 1999 and the closing date, except for fractional shares which will
receive a proportional amount of cash (the Merger "Consideration"). As of
December , 1998, the estimated value of USBN common stock is $ per share of BFC
common stock.

        Columbia Financial Advisors, Inc. ("CFAI"), as a part of its investment
banking services, is periodically engaged in the valuation of banks and advises
the directors, officers and shareholders of both public and private banks and
thrift institutions with respect to the fairness, from a financial point of
view, of the consideration to be received in transactions such as that proposed
by the Agreement. With particular regard to our qualifications for rendering an
opinion as to the fairness, from a financial point of view, of the Consideration
to be received by holders of the shares from USBN pursuant to the Merger, CFAI
has advised Washington and Oregon community banks regarding fairness of capital
transactions. BFC has agreed to pay CFAI a fee for this opinion letter.



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<PAGE>   137



Board of Directors
Bancwest Financial Corporation
December __, 1998



        In connection with rendering this opinion, we have, among other things:
(I) reviewed the Agreement; (ii) reviewed BFC's financial information for the
twelve months ended December 31, 1997 and nine months ended September 30, 1998;
(iii) reviewed certain internal financial analyses and certain other forecasts
for BFC prepared by and reviewed with the management of BFC; (iv) conducted
interviews with senior management of BFC regarding the past and current business
operations, results thereof, financial condition and future prospects of BFC;
(v) reviewed the current market environment generally and the banking
environment in particular; (vi) reviewed the prices paid in certain recent
mergers and acquisitions in the banking industry on a regional basis; (vii)
reviewed USBN's audited financial information for the fiscal year ended December
31, 1997 and the quarter ended June 30, 1998 including the Form 10-KSB and Form
10-QSB filed with the U.S. Securities and Exchange Commission; (ix) reviewed the
price ranges and dividend history for USBN common stock; (x) and reviewed such
other information, studies and analyses and performed such other investigations
and took into account such other matters as we deemed appropriate.

        In conducting our review and arriving at our opinion, we have relied on
the accuracy and completeness of all information supplied or otherwise made
available to us, and we have not independently verified such information nor
have we undertaken an independent appraisal of the assets or liabilities of the
BFC or USBN. With respect to the financial forecasts referred to above, we have
assumed that they have been reasonably prepared on bases reflecting the best
currently available estimates and judgment of the senior management of BFC. This
opinion is necessarily based upon circumstances and conditions as they exist and
can be evaluated as of the date of this letter.

        This opinion is based upon the information available to us and facts and
circumstances as they exist and are subject to evaluation on the date hereof. We
are not expressing any opinion herein as to the prices at which shares of USBN
Common Stock have traded or may trade at any future date.

        This opinion is not intended to be and does not constitute a
recommendation to any stockholder as to how such stockholder should vote with
respect to the merger.

        In reliance upon and subject to the foregoing, it is our opinion that,
as of the date hereof, the Merger Consideration to be received by the
shareholders of BFC pursuant to the Agreement is fair, from a financial point of
view, to the shareholders of BFC.



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<PAGE>   138


Board of Directors
Bancwest Financial Corporation
December __, 1998


        We hereby consent to the reference to our firm in the proxy statement or
prospectus related to the merger transaction and to the inclusion of our opinion
as an exhibit to the proxy statement or prospectus related to the merger
transaction.

                                       Very truly yours,

                                       COLUMBIA FINANCIAL ADVISORS, INC.


                                       By:
                                          --------------------------------------
                                          Robert J. Rogowski
                                          Principal



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<PAGE>   139

                                                                      APPENDIX D

                             STOCK OPTION AGREEMENT

        This Stock Option Agreement ("Agreement"), dated as of November 10,
1998, is between UNITED SECURITY BANCORPORATION ("USBN") and BANCWEST FINANCIAL
CORPORATION ("Bancwest").

                                    RECITALS

        Bancwest and USBN have executed an Agreement and Plan of Merger
("Plan"), of even date with this Agreement, under which Bancwest will merge with
and into USBN, and Bank of the West, the wholly owned subsidiary of Bancwest,
will become a wholly owned subsidiary of USBN upon completion of the merger
("Merger") contemplated in the Plan.

        By negotiating and executing the Plan and by taking actions necessary or
appropriate to effect the transactions contemplated by the Plan, USBN has
incurred and will incur substantial direct and indirect costs (including,
without limitation, the costs of management and employee time) and will forgo
the pursuit of certain alternative investments and transactions.

                                    AGREEMENT

        THEREFORE, in consideration of the promises set forth in this Agreement
and in the Plan, the parties agree as follows:

 1.     Grant of Option. Subject to the terms and conditions set forth in this
        Agreement, Bancwest irrevocably grants an option ("Option") to USBN to
        purchase an aggregate of 90,502 authorized but unissued shares of
        Bancwest's capital stock ("Common Stock") (which if issued, and assuming
        exercise of outstanding options to acquire the Common Stock, would
        represent approximately 19.9% of total stock issued and outstanding), at
        a per share price of $45.00 ("Option Price").

 2.     Exercise of Option. Subject to the provisions of this Section 2 and of
        Section 1313a of this Agreement, this Option may be exercised by USBN or
        any transferee as set forth in Section 5 of this Agreement, in whole or
        in part, at any time, or from time to time in any of the following
        circumstances:

        a.      Bancwest or its board of directors executes a written agreement
                or recommends to Bancwest shareholders to approve or otherwise
                vote in favor of an agreement (other than the Plan) under which
                any entity, person or group (collectively "Person"), within the
                meaning of Section 13(d)(3) of the Securities Exchange Act of
                1934, as amended ("Exchange Act"), would: (1) merge or
                consolidate with, acquire 51% or more of the assets or
                liabilities of, or enter into any similar transaction with
                Bancwest, or (2) purchase or otherwise acquire (including by
                merger, reorganization, consolidation, share exchange or any
                similar transaction) securities representing 10% or more of
                Bancwest's voting shares;



                                      D-1


<PAGE>   140


        b.      any Person (other than USBN or any of its subsidiaries and other
                than any Person beneficially owning as of the date of this
                Agreement 10% or more of Bancwest's voting shares) acquires the
                beneficial ownership or the right to acquire beneficial
                ownership of securities which, when aggregated with other such
                securities owned by such Person, represents 10% or more of the
                voting shares of Bancwest (the term "beneficial ownership" for
                purposes of this Agreement has the meaning set forth in Section
                13(d) of the Exchange Act, and the regulations promulgated under
                the Exchange Act); notwithstanding the foregoing, the Option
                will not be exercisable in the circumstances described above in
                this subsection 2 if a Person acquires the beneficial ownership
                of securities which, when aggregated with other such securities
                owned by such Person, represents 10% or more, but less than 25%,
                of Bancwest's voting shares and the transaction does not result
                in, and is not presumed to constitute, "control" as defined
                under Section 7(j) of the Federal Deposit Insurance Act or 12
                CFR Part 303.4; or

        c.      failure of the shareholders to approve the Merger by the
                required affirmative vote at a meeting of the shareholders,
                after any Person (other than USBN or a subsidiary of USBN)
                announces publicly or communicates, in writing, to Bancwest a
                proposal to (1) acquire Bancwest (by merger, reorganization,
                consolidation, the purchase of 51% or more of its assets or
                liabilities, or any other similar transaction), (2) purchase or
                otherwise acquire securities representing 25% or more of the
                voting shares of Bancwest or (3) change the composition of the
                board of directors of Bancwest.

        It is understood and agreed that the Option will become exercisable on
        the occurrence of any of the above-described circumstances even though
        the circumstance occurred as a result, in part or in whole, of the board
        of Bancwest complying with its fiduciary duties.

        Notwithstanding the foregoing, the Option may not be exercised if either
        (1) any applicable and required governmental approvals have not been
        obtained with respect to such exercise or if such exercise would violate
        any applicable regulatory restrictions, or (2) at the time of exercise,
        USBN is failing in any material respect to perform or observe its
        material covenants or conditions under the Plan, unless the reason for
        such failure is that Bancwest is failing to perform or observe its
        covenants or conditions under the Plan.

 3.     Notice, Time and Place of Exercise. Each time that USBN or any
        transferee wishes to exercise any portion of the Option, USBN or such
        transferee will give written notice of its intention to exercise the
        Option specifying the number of shares as to which the Option is being
        exercised ("Option Shares") and the place and date for the closing of
        the exercise (which date may not be later than ten business days from
        the date such notice is mailed). If any law, regulation or other
        restriction will not permit such exercise to be consummated during this
        ten-day period, the date for the closing of such exercise will be within
        five days following the cessation of the restriction on consummation.




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<PAGE>   141


 4.     Payment and Delivery of Certificate(s). At any closing for an exercise
        of the Option or any portion thereof, (a) USBN and Bancwest will each
        deliver to the other certificates as to the accuracy, as of the closing
        date, of their respective representations and warranties under this
        Agreement, (b) USBN or the transferees will pay the aggregate purchase
        price for the shares of Common Stock to be purchased by delivery of a
        certified or bank cashier's check in immediately available funds payable
        to the order of Bancwest, and (c) Bancwest will deliver to USBN or the
        transferees a certificate or certificates representing the shares so
        purchased.

 5.     Transferability of the Option and Option Shares. Before the Option, or a
        portion of the Option, becomes exercisable in accordance with the
        provisions of Section 2 of this Agreement, neither the Option nor any
        portion of the Option will be transferable. If any of the events or
        circumstances set forth in Sections 2a through c above occur, USBN may
        freely transfer, subject to applicable federal and state securities
        laws, the Option or any portion of the Option, or any of the Option
        Shares.

        For purposes of this Agreement, a reorganization or consolidation of
        USBN (whether or not USBN is the surviving entity) or an acquisition of
        USBN will not be deemed a transfer.

 6.     Representations, Warranties and Covenants of Bancwest. Bancwest
        represents and warrants to USBN as follows:

        a.      Due Authorization. This Agreement has been duly authorized by
                all necessary corporate action on the part of Bancwest, has been
                duly executed by a duly authorized officer of Bancwest and
                constitutes a valid and binding obligation of Bancwest. No
                shareholder approval by Bancwest shareholders is required by
                applicable law or otherwise before the exercise of the Option in
                whole or in part.

        b.      Option Shares. Bancwest has taken all necessary corporate and
                other action to authorize and reserve and to permit it to issue
                and, at all times from the date of this Agreement to such time
                as the obligation to deliver shares under this Agreement
                terminates, will have reserved for issuance, at the closing(s)
                upon exercise of the Option, or any portion of the Option, the
                Option Shares (subject to adjustment, as provided in Section 8
                below), all of which, upon issuance under this Agreement, will
                be duly and validly issued, fully paid and nonassessable, and
                will be delivered free and clear of all claims, liens,
                encumbrances and security interests, including any preemptive
                right of any of the shareholders of Bancwest.

        c.      No Conflicts. Neither the execution and delivery of this
                Agreement nor the consummation of the transactions contemplated
                by it will violate or result in any violation of or be in
                conflict with or constitute a default under any term of the
                articles of incorporation or bylaws of Bancwest or any
                agreement, instrument, judgment, decree, law, rule or order
                applicable to Bancwest or any subsidiary of Bancwest or to which
                Bancwest or any such subsidiary is a party.



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<PAGE>   142


        d.      Notification of Record Date. At any time from and after the date
                of this Agreement until the Option is no longer exercisable,
                Bancwest will give USBN or any transferee 30 days prior written
                notice before setting the record date for determining the
                holders of record of the Common Stock entitled to vote on any
                matter, to receive any dividend or distribution or to
                participate in any rights offering or other matters, or to
                receive any other benefit or right, with respect to the Common
                Stock.

 7.     Representations, Warranties and Covenants of USBN. USBN represents and
        warrants to Bancwest as follows:

        a.      Due Authorization. This Agreement has been duly authorized by
                all necessary corporate action on the part of USBN, has been
                duly executed by a duly authorized officer of USBN and
                constitutes a valid and binding obligation of USBN.

        b.      Transfers of Common Stock. No shares of Common Stock acquired
                upon exercise of the Option will be transferred except in a
                transaction registered or exempt from registration under any
                applicable securities laws.

        c.      No Conflicts. Neither the execution and delivery of this
                Agreement nor the consummation of the transactions contemplated
                by it will violate or result in any violation of or be in
                conflict with or constitute a default under any term of the
                certificate of incorporation or bylaws of USBN or any agreement,
                instrument, judgment, decree, law, rule or order applicable to
                USBN or any subsidiary of USBN or to which USBN or any such
                subsidiary is a party.

 8.     Adjustment Upon Changes in Capitalization. In the event of any change in
        the Common Stock by reason of stock dividends, split-ups, mergers,
        reorganizations, recapitalizations, combinations, exchanges of shares or
        the like, the number and kind of shares or securities subject to the
        Option and the purchase price per share of Common Stock will be
        appropriately adjusted. If, before the Option terminates or is
        exercised, Bancwest is acquired by another party, consolidates with or
        merges into another corporation or liquidates, USBN or any transferee
        will thereafter receive, upon exercise of the Option, the securities or
        properties to which a holder of the number of shares of Common Stock
        then deliverable upon the exercise thereof would have been entitled upon
        such acquisition, consolidation, merger, reorganization or liquidation,
        and Bancwest will take all steps in connection with such acquisition,
        consolidation, merger, reorganization or liquidation as may be necessary
        to assure that the provisions of this Agreement will thereafter be
        applicable, as nearly as reasonably may be practicable, in relation to
        any securities or property thereafter deliverable upon exercise of the
        Option.

 9.     Nonassignability. This Agreement binds and inures to the benefit of the
        parties and their successors. This Agreement is not assignable by either
        party, but USBN may transfer the Option, the Option Shares or any
        portion of the Option or Option Shares in accordance with Section 5. A
        merger, reorganization or consolidation of USBN (whether or not 




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<PAGE>   143


        USBN is the surviving entity) or an acquisition of USBN will not be
        deemed an assignment or transfer.

10.     Regulatory Restrictions. Bancwest will use its best efforts to obtain or
        to cooperate with USBN or any transferee in obtaining all necessary
        regulatory consents, approvals, waivers or other action (whether
        regulatory, corporate or other) to permit the acquisition of any or all
        Option Shares by USBN or any transferee.

11.     Remedies. Bancwest agrees that if for any reason USBN or any transferee
        will have exercised its rights under this Agreement and Bancwest will
        have failed to issue the Option Shares to be issued upon such exercise
        or to perform its other obligations under this Agreement, unless such
        action would violate any applicable law or regulation by which Bancwest
        is bound, then USBN or any transferee will be entitled to specific
        performance and injunctive and other equitable relief. USBN agrees that
        if it fails to perform any of its obligations under this Agreement, then
        Bancwest will be entitled to specific performance and injunctive and
        other equitable relief. This provision is without prejudice to any other
        rights that Bancwest or USBN or any transferee may have against the
        other party for any failure to perform its obligations under this
        Agreement.

12.     No Rights as Shareholder. This Option, before it is exercised, will not
        entitle its holder to any rights as a shareholder of Bancwest at law or
        in equity. Specifically, this Option, before it is exercised, will not
        entitle the holder to vote on any matter presented to the shareholders
        of Bancwest or, except as provided in this Agreement, to any notice of
        any meetings of shareholders or any other proceedings of Bancwest.

13.     Miscellaneous.

        a.      Termination. This Agreement and the Option, to the extent not
                previously exercised, will terminate upon the earliest of (1)
                December 31, 1999; (2) the mutual agreement of the parties to
                this Agreement; (3) 31 days after the date on which any
                application for regulatory approval for the Merger has been
                denied, but if before the expiration of the 31-day period,
                Bancwest or USBN is engaged in litigation or an appeal procedure
                relating to an attempt to obtain approval of the Merger, this
                Agreement will not terminate until the later of (i) December 31,
                1999, or (ii) 31 days after the completion of the litigation and
                appeal procedure; (4) the 30th day following the termination of
                the Plan for any reason other than a material noncompliance or
                default by USBN with respect to its obligations under it; or (5)
                the date of termination of the Plan if the termination is due to
                a material noncompliance or default by USBN with respect to its
                obligations under it; but if the Option becomes exercisable
                pursuant to Section 2 of this Agreement before the termination
                of this Agreement, then the exercise will promptly close under
                Section 4 of this Agreement, even though that closing date is
                after the termination of this Agreement; and if the Option is
                transferred pursuant to Section 5 of this Agreement before the
                termination of this Agreement, the Option may be exercised by
                the transferee at any time within 31 days after the date of
                termination even



                                      D-5


<PAGE>   144


                though such exercise or the closing of such exercise occurs
                after the termination of this Agreement.

        b.      Amendments. This Agreement may not be modified, amended, altered
                or supplemented, except upon the execution and delivery of a
                written agreement executed by the parties.

        c.      Severability of Terms. Any provision of this Agreement that is
                invalid, illegal or unenforceable is ineffective only to the
                extent of the invalidity, illegality or unenforceability without
                affecting in any way the remaining provisions or rendering any
                other provisions of this Agreement invalid, illegal or
                unenforceable. Without limiting the generality of the foregoing,
                if the right of USBN or any transferee to exercise the Option in
                full for the total number of shares of Common Stock or other
                securities or property issuable upon the exercise of the Option
                is limited by applicable law, or otherwise, USBN or any
                transferee may, nevertheless, exercise the Option to the fullest
                extent permissible.

        d.      Notices. All notices, requests, claims, demands and other
                communications under this Agreement must be in writing and must
                be given (and will be deemed to have been duly received if so
                given) by delivery, by cable, telecopies or telex, or by
                registered or certified mail, postage prepaid, return receipt
                requested, to the respective parties at the addresses below, or
                to such other address as either party may furnish to the other
                in writing. Change of address notices will be effective upon
                receipt.

                        If to Bancwest to:

                             Bancwest Financial Corporation
                             P.O. Box 1597
                             Walla Walla, Washington 99362
                             Attn: Wes E. Colley

                        With a copy to:

                             Glen P. Garrison
                             Keller Rohrback L.L.P
                             1201 Third Avenue, Suite 3200
                             Seattle, Washington 98101-3052

                        If to USBN, to:

                             United Security Bancorporation
                             N. 9506 Newport Hwy
                             Spokane, Washington 99218
                             Attn: William C. Dashiell and Richard C. Emery



                                      D-6


<PAGE>   145


                        With a copy to:

                             Stephen M. Klein, Esq.
                             Graham & Dunn, P.C.
                             1420 Fifth Avenue, 33rd Floor
                             Seattle, WA  98101-2390

        a.      Governing Law and Venue. The parties intend this Agreement and
                the Option, in all respects, including all matters of
                construction, validity and performance, to be governed by the
                laws of the State of Washington, without giving effect to
                conflicts of law principles. Any actions brought by either party
                against the other arising under this Agreement must be filed in
                Spokane County, Washington, and each party consents to personal
                jurisdiction in Spokane County.

        b.      Counterparts. This Agreement may be executed in several
                counterparts, each of which is an original, and all of which
                together constitute one and the same agreement.

        c.      Effects of Headings. The section headings in this Agreement are
                for convenience only and do not affect the meaning of its
                provisions.

        Dated November 10, 1998:

                                       UNITED SECURITY BANCORPORATION


                                       By: /s/ William C. Dashiell
                                          --------------------------------------
                                          William C. Dashiell
                                       Its: Chairman


                                       By: /s/ Richard C. Emery
                                          --------------------------------------
                                          Richard C. Emery
                                       Its: President and Chief Executive
                                            Officer


                                       BANCWEST FINANCIAL CORPORATION


                                       By: /s/ Wes E. Colley
                                          --------------------------------------
                                          Wes E. Colley
                                       Its: Chairman and President



                                      D-7


<PAGE>   146

                                                                      APPENDIX E

                 TITLE 23B. WASHINGTON BUSINESS CORPORATION ACT
                       CHAPTER 23B.13. DISSENTERS' RIGHTS

SECTION 23B.13.010    DEFINITIONS.  As used in this chapter:

        (1) "Corporation" means the issuer of the shares held by a dissenter
before the corporate action, or the surviving or acquiring corporation by merger
or share exchange of that issuer.

        (2) "Dissenter" means a shareholder who is entitled to dissent from
corporate action under RCW 23B.13.020 and who exercises that right when and in
the manner required by RCW 23B.13.200 through 23B.13.280.

        (3) "Fair value," with respect to a dissenter's shares, means the value
of the shares immediately before the effective date of the corporate action to
which the dissenter objects, excluding any appreciation or depreciation in
anticipation of the corporate action unless exclusion would be inequitable.

        (4) "Interest" means interest from the effective date of the corporate
action until the date of payment, at the average rate currently paid by the
corporation on its principal bank loans or, if none, at a rate that is fair and
equitable under all the circumstances.

        (5) "Record shareholder" means the person in whose name shares are
registered in the records of a corporation or the beneficial owner of shares to
the extent of the rights granted by a nominee certificate on file with a
corporation.

        (6) "Beneficial shareholder" means the person who is a beneficial owner
of shares held in a voting trust or by a nominee as the record shareholder.

        (7) "Shareholder" means the record shareholder or the beneficial
shareholder.

SECTION 23B.13.020    RIGHT TO DISSENT.

        (1) A shareholder is entitled to dissent from, and obtain payment of the
fair value of the shareholder's shares in the event of, any of the following
corporate actions:

               (a) Consummation of a plan of merger to which the corporation is
a party (i) if shareholder approval is required for the merger by RCW
23B.11.030, 23B.11.080, or the articles of incorporation and the shareholder is
entitled to vote on the merger, or (ii) if the corporation is a subsidiary that
is merged with its parent under RCW 23B.11.040;

               (b) Consummation of a plan of share exchange to which the
corporation is a party as the corporation whose shares will be acquired, if the
shareholder is entitled to vote on the plan;

               (c) Consummation of a sale or exchange of all, or substantially
all, of the property of the corporation other than in the usual and regular
course of business, if the shareholder is entitled to vote on the sale or
exchange, including a sale in dissolution, but not including a sale pursuant to
court order or a sale for cash pursuant to a plan by which all or substantially
all of the net proceeds of the sale will be distributed to the shareholders
within one year after the date of sale;



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               (d) An amendment of the articles of incorporation that materially
reduces the number of shares owned by the shareholder to a fraction of a share
if the fractional share so created is to be acquired for cash under RCW
23B.06.040; or

               (e) Any corporate action taken pursuant to a shareholder vote to
the extent the articles of incorporation, bylaws, or a resolution of the board
of directors provides that voting or nonvoting shareholders are entitled to
dissent and obtain payment for their shares.

        (2) A shareholder entitled to dissent and obtain payment for the
shareholder's shares under this chapter may not challenge the corporate action
creating the shareholder's entitlement unless the action fails to comply with
the procedural requirements imposed by this title, RCW 25.10.900 through
25.10.955, the articles of incorporation, or the bylaws, or is fraudulent with
respect to the shareholder or the corporation.

        (3) The right of a dissenting shareholder to obtain payment of the fair
value of the shareholder's shares shall terminate upon the occurrence of any one
of the following events:

               (a)    The proposed corporate action is abandoned or rescinded;

               (b) A court having jurisdiction permanently enjoins or sets aside
the corporate action; or

               (c) The shareholder's demand for payment is withdrawn with the
written consent of the corporation. 1991 c 269 Section 37; 1989 c 165 Section
141.

SECTION 23B.13.030 DISSENT BY NOMINEES AND BENEFICIAL OWNERS.

        (1) A record shareholder may assert dissenters' rights as to fewer than
all the shares registered in the shareholder's name only if the shareholder
dissents with respect to all shares beneficially owned by any one person and
notifies the corporation in writing of the name and address of each person on
whose behalf the shareholder asserts dissenters' rights. The rights of a partial
dissenter under this subsection are determined as if the shares as to which the
dissenter dissents and the dissenter's other shares were registered in the names
of different shareholders.

        (2) A beneficial shareholder may assert dissenters' rights as to shares
held on the beneficial shareholder's behalf only if:

               (a) The beneficial shareholder submits to the corporation the
record shareholder's written consent to the dissent not later than the time the
beneficial shareholder asserts dissenters' rights; and

               (b) The beneficial shareholder does so with respect to all shares
of which such shareholder is the beneficial shareholder or over which such
shareholder has power to direct the vote. 1989 c 165 Section 142.

SECTION 23B.13.200    NOTICE OF DISSENTERS' RIGHTS.

        (1) If proposed corporate action creating dissenters' rights under RCW
23B.13.020 is submitted to a vote at a shareholders' meeting, the meeting notice
must state that shareholders are or may be entitled to assert dissenters' rights
under this chapter and be accompanied by a copy of this chapter.



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        (2) If corporate action creating dissenters' rights under RCW 23B.13.020
it taken without a vote of shareholders, the corporation, within ten days after
[the] effective date of such corporate action, shall notify in writing all
shareholders entitled to assert dissenters' rights that the action was taken and
send them the dissenters' notice described in RCW 23B.13.220. 1989 c 165 Section
143.

SECTION 23B.13.210 NOTICE OF INTENT TO DEMAND PAYMENT.

        (1) If proposed corporate action creating dissenters' rights under RCW
23B.13.020 is submitted to a vote at a shareholders' meeting, a shareholder who
wishes to assert dissenters' rights must (a) deliver to the corporation before
the vote is taken written notice of the shareholder's intent to demand payment
for the shareholder's shares if the proposed action is effected, and (b) not
vote such shares in favor of the proposed action.

        (2) A shareholder who does not satisfy the requirements of subsection
(1) of this section is not entitled to payment for the shareholder's shares
under this chapter. 1989 c 165 Section 144.

SECTION 23B.13.220    DISSENTERS' NOTICE.

        (1) If proposed corporate action creating dissenters' rights under RCW
23B.13.020 is authorized at a shareholders' meeting, the corporation shall
deliver a written dissenters' notice to all shareholders who satisfied the
requirements of RCW 23B.13.210.

        (2) The dissenters' notice must be sent within ten days after the
effective date of the corporate action, and must:

               (a) State where the payment demand must be sent and where and
when certificates for certificated shares must be deposited;

               (b) Inform holders of uncertificated shares to what extent
transfer of the shares will be restricted after the payment demand is received;

               (c) Supply a form for demanding payment that includes the date of
the first announcement to news media or to shareholders of the terms of the
proposed corporate action and requires that the person asserting dissenters'
rights certify whether or not the person acquired beneficial ownership of the
shares before that date;

               (d) Set a date by which the corporation must receive the payment
demand, which date may not be fewer than thirty nor more than sixty days after
the date the notice in subsection (1) of this section is delivered; and

               (e) Be accompanied by a copy of this chapter.

SECTION 23B.13.230    DUTY TO DEMAND PAYMENT.

        (1) A shareholder sent a dissenters' notice described in RCW 23B.13.220
must demand payment, certify whether the shareholder acquired beneficial
ownership of the shares before the date required to be set forth in the
dissenters' notice pursuant to RCW 23B.13.220(2)(c), and deposit the
shareholder's certificates in accordance with the terms of the notice.



                                      E-3


<PAGE>   149


        (2) The shareholder who demands payment and deposits the shareholder's
share certificates under subsection (1) of this section retains all other rights
of a shareholder until the proposed corporate action is effected.

        (3) A shareholder who does not demand payment or deposit the
shareholder's share certificates where required, each by the date set in the
dissenters' notice, is not entitled to payment for the shareholder's shares
under this chapter.


SECTION 23B.13.240    SHARE RESTRICTIONS.

        (1) The corporation may restrict the transfer of uncertificated shares
from the date the demand for their payment is received until the proposed
corporate action is effected or the restriction is released under RCW
23B.13.260.

        (2) The person for whom dissenters' rights are asserted as to
uncertificated shares retains all other rights of a shareholder until the
effective date of the proposed corporate action.

SECTION 23B.13.250    PAYMENT.

        (1) Except as provided in RCW 23B.13.270, within thirty days of the
later of the effective date of the proposed corporate action, or the date the
payment demand is received, the corporation shall pay each dissenter who
complied with RCW 23B.13.230 the amount the corporation estimates to be the fair
value of the shareholders' shares, plus accrued interest.

        (2) The payment must be accompanied by:

               (a) The corporation's balance sheet as of the end of a fiscal
year ending not more than sixteen months before the date of payment, an income
statement for that year, a statement of changes in shareholders' equity for that
year, and the latest available interim financial statements, if any;

               (b) An explanation of how the corporation estimated the fair
value of the shares;

               (c) An explanation of how the interest was calculated;

               (d) A statement of the dissenter's right to demand payment under
RCW 23B.13.280; and

               (e) A copy of this chapter.

SECTION 23B.13.260    FAILURE TO TAKE ACTION.

        (1) If the corporation does not effect the proposed action within sixty
days after the date set for demanding payment and depositing share certificates,
the corporation shall return the deposited certificates and release any transfer
restrictions imposed on uncertificated shares.

        (2) If after returning deposited certificates and releasing transfer
restrictions, the corporation wishes to undertake the proposed action, it must
send a new dissenters' notice under RCW 23B.13.220 and repeat the payment demand
procedure.



                                      E-4


<PAGE>   150


SECTION 23B.13.270    AFTER-ACQUIRED SHARES.

        (1) A corporation may elect to withhold payment required by RCW
23B.13.250 from a dissenter unless the dissenter was the beneficial owner of the
shares before the date set forth in the dissenters' notice as the date of the
first announcement to news media or to shareholders of the terms of the proposed
corporate action.

        (2) To the extent the corporation elects to withhold payment under
subsection (1) of this section, after taking the proposed corporate action, it
shall estimate the fair value of the shares, plus accrued interest, and shall
pay this amount to each dissenter who agrees to accept it in full satisfaction
of the dissenter's demand. The corporation shall send with its offer an
explanation of how it estimated the fair value of the shares, an explanation of
how the interest was calculated, and a statement of the dissenter's right to
demand payment under RCW 23B.13.280.

SECTION 23B.13.280 PROCEDURE IF SHAREHOLDER DISSATISFIED WITH PAYMENT OR OFFER.

        (1) A dissenter may notify the corporation in writing of the dissenter's
own estimate of the fair value of the dissenter's shares and amount of interest
due, and demand payment of the dissenter's estimate, less any payment under RCW
23B.13.250, or reject the corporation's offer under RCW 23B.13.270 and demand
payment of the dissenter's estimate of the fair value of the dissenter's shares
and interest due, if:

               (a) The dissenter believes that the amount paid under RCW
23B.13.250 or offered under RCW 23B.13.270 is less than the fair value of the
dissenter's shares or that the interest due is incorrectly calculated;

               (b) The corporation fails to make payment under RCW 23B.13.250
within sixty days after the date set for demanding payment; or

               (c) The corporation does not effect the proposed action and does
not return the deposited certificates or release the transfer restrictions
imposed on uncertificated shares within sixty days after the date set for
demanding payment.

        (2) A dissenter waives the right to demand payment under this section
unless the dissenter notifies the corporation of the dissenter's demand in
writing under subsection (1) of this section within thirty days after the
corporation made or offered payment for the dissenter's shares.

SECTION 23B.13.300    COURT ACTION.

        (1) If a demand for payment under RCW 23B.13.280 remains unsettled, the
corporation shall commence a proceeding within sixty days after receiving the
payment demand and petition the court to determine the fair value of the shares
and accrued interest. If the corporation does not commence the proceeding within
the sixty-day period, it shall pay each dissenter whose demand remains unsettled
the amount demanded.

        (2) The corporation shall commence the proceeding in the superior court
of the county where a corporation's principal office, or, if none in this state,
its registered office, is located. If the corporation is a foreign corporation
without a registered office in this state, it shall commence the proceeding in
the county in this state where the registered office of the domestic corporation
merged with or whose shares were acquired by the foreign corporation was
located.



                                      E-5


<PAGE>   151


        (3) The corporation shall make all dissenters, whether or not residents
of this state, whose demands remain unsettled, parties to the proceeding as in
an action against their shares and all parties must be served with a copy of the
petition. Nonresidents may be served by registered or certified mail or by
publication as provided by law.

        (4) The corporation may join as a party to the proceeding any
shareholder who claims to be a dissenter but who has not, in the opinion of the
corporation, complied with the provisions of this chapter. If the court
determines that such shareholder has not complied with the provisions of this
chapter, the shareholder shall be dismissed as a party.

        (5) The jurisdiction of the court in which the proceeding is commenced
under subsection (2) of this section is plenary and exclusive. The court may
appoint one or more persons as appraisers to receive evidence and recommend
decision on the question of fair value. The appraisers have the powers described
in the order appointing them, or in any amendment to it. The dissenters are
entitled to the same discovery rights as parties in other civil proceedings.

        (6) Each dissenter made a party to the proceeding is entitled to
judgment (a) for the amount, if any, by which the court finds the fair value of
the dissenter's shares, plus interest, exceeds the amount paid by the
corporation, or (b) for the fair value, plus accrued interest, of the
dissenter's after-acquired shares for which the corporation elected to withhold
payment under RCW 23B.13.270.

SECTION 23B.13.310 COURT COSTS AND COUNSEL FEES.

        (1) The court in a proceeding commenced under RCW 23B.13.300 shall
determine all costs of the proceeding, including the reasonable compensation and
expenses of appraisers appointed by the court. The court shall assess the costs
against the corporation, except that the court may assess the costs against all
or some of the dissenters, in amounts the court finds equitable, to the extent
the court finds the dissenters acted arbitrarily, vexatiously, or not in good
faith in demanding payment under RCW 23B.13.280.

        (2) The court may also assess the fees and expenses of counsel and
experts for the respective parties, in amounts the court finds equitable:

               (a) Against the corporation and in favor of any or all dissenters
if the court finds the corporation did not substantially comply with the
requirements of RCW 23B.13.200 through 23B.13.280; or

               (b) Against either the corporation or a dissenter, in favor of
any other party, if the court finds that the party against whom the fees and
expenses are assessed acted arbitrarily, vexatiously, or not in good faith with
respect to the rights provided by chapter 23B.13 RCW.

        (3) If the court finds that the services of counsel for any dissenter
were of substantial benefit to other dissenters similarly situated, and that the
fees for those services should not be assessed against the corporation, the
court may award to these counsel reasonable fees to be paid out of the amounts
awarded the dissenters who were benefited.



                                      E-6


<PAGE>   152

                                     PART II

                     INFORMATION NOT REQUIRED IN PROSPECTUS

ITEM 20.  INDEMNIFICATION OF DIRECTORS AND OFFICERS

         Sections 23B.08.500 through 23B.08.600 RCW contain specific provisions
relating to indemnification of directors and officers of Washington
corporations. In general, the statute provides that (i) a corporation must
indemnify a director or officer who is wholly successful in his defense of a
proceeding to which he is a party because of his status as such, unless limited
by the articles of incorporation, and (ii) a corporation may indemnify a
director or officer if he is not wholly successful in such defense, if it is
determined as provided in the statute that the director meets a certain standard
of conduct, provided when a director is liable to the corporation, the
corporation may not indemnify him. The statute also permits a director or
officer of a corporation who is a party to a proceeding to apply to the courts
for indemnification or advance of expenses, unless the articles of incorporation
provide otherwise, and the court may order indemnification or advance of
expenses under certain circumstances set forth in the statute. The statute
further provides that a corporation may in its articles of incorporation or
bylaws or by resolution provide indemnification in addition to that provided by
the statute, subject to certain conditions set forth in the statute.

         Pursuant to USBN's Bylaws, USBN will indemnify the officers, directors
and employees of USBN with respect to expenses, settlements, judgments, and
fines in suits in which such person has been made a party by reason of the fact
that he or she is or was an officer, director or employee of USBN. No such
indemnification may be given if the acts or omissions of the person are adjudged
to have been taken (or failed to have been taken) in negligence or bad faith.

ITEM 21.  EXHIBITS AND FINANCIAL STATEMENT SCHEDULES

         (a) The exhibits are listed on the accompanying "Exhibit Index."

         (b) Financial Statement Schedules. None.

         (c) The opinions of the financial advisors to USBN and BFC are set
forth as APPENDICES B AND C to this Prospectus/Joint Proxy Statement.

ITEM 22.  UNDERTAKINGS

         (a) The undersigned registrant hereby undertakes:

                  (1) To file, during any period in which it offers or sells
securities, a post-effective amendment to this registration statement to:

                           (i) Include any prospectus required by Section
10(a)(3) of the 1933 Act;

                           (ii) Reflect in the prospectus any facts or events
which, individually or together, represent a fundamental change in the
information in the registration statement. Notwithstanding the foregoing, any
increase or decrease in volume of securities offered (if the total dollar value
of securities offered would not exceed that which was registered) and any
deviation from the low or high end of the estimated maximum offering range may
be reflected in the form of prospectus filed with the SEC pursuant to Rule
424(b) if, in the aggregate, the changes in volume and price represent no more
than a 20% change in the maximum aggregate offering price set forth in the
"Calculation of Registration Fee" table in the effective registration statement;
and



                                      II-1


<PAGE>   153


                           (iii) Include any additional or changed information
on the plan of distribution;

                  (2) For determining liability under the 1933 Act, to treat
each such post-effective amendment as a new registration statement of the
securities offered, and the offering of the securities at that time shall be
deemed to be the initial bona fide offering.

                  (3) To file a post-effective amendment to remove from
registration any of the securities that remain unsold at the end of the
offering.

         (b) Insofar as indemnification for liabilities arising under the
Securities Act of 1933 may be permitted to directors, officers and controlling
persons of the registrant pursuant to the foregoing provisions, or otherwise,
the registrant has been advised that in the opinion of the Securities and
Exchange Commission such indemnification is against public policy as expressed
in the Act and is, therefore, unenforceable. In the event that a claim for
indemnification against such liabilities (other than the payment by the
registrant of expenses incurred or paid by a director, officer or controlling
person of the registrant in the successful defense of any action, suit or
proceeding) is asserted by such director, officer or controlling person in
connection with the securities being registered, the registrant will, unless in
the opinion of its counsel the matter has been settled by controlling precedent,
submit to a court of appropriate jurisdiction the question whether such
indemnification by it is against public policy as expressed in the Act and will
be governed by the final adjudication of such issue.

         (c) The undersigned registrant hereby undertakes to respond to requests
for information that is incorporated by reference into the prospectus pursuant
to Item 4, 10(b), 11, or 13 of this form, within one business day of receipt of
such request, and to send the incorporated documents by first class mail or
other equally prompt means. This includes information contained in documents
filed subsequent to the effective date of the registration statement through the
date of responding to the request.

         (d) The undersigned registrant hereby undertakes to supply by means of
a post-effective amendment all information concerning a transaction, and the
company being acquired involved therein, that was not the subject of and
included in the registration statement when it became effective.



                                      II-2


<PAGE>   154



                                   SIGNATURES

         Pursuant to the requirements of the 1933 Act, the Registrant has duly
caused this Registration Statement to be signed on its behalf by the
undersigned, thereunto duly authorized, in Spokane, Washington on December 11th,
1998.

                                       UNITED SECURITY BANCORPORATION


                                       By: /s/ WILLIAM C. DASHIELL
                                          --------------------------------------
                                               William C. Dashiell
                                               Chairman

                                       By: /s/ RICHARD C. EMERY
                                          --------------------------------------
                                               Richard C. Emery, President and
                                               Chief Executive Officer


                                POWER OF ATTORNEY

         Each person whose individual signature appears below hereby authorizes
and appoints William C. Dashiell, Richard C. Emery and Chad Galloway, and either
two of them together, acting with full power of substitution and full power to
so act, as his true and lawful attorney-in-fact and agent to act in his name,
place and stead and to execute in the name and on behalf of each person,
individually and in each capacity stated below, and to file any and all
amendments to this Registration Statement, including any and all post-effective
amendments.

         Pursuant to the requirements of the 1933 Act, this Power of Attorney
has been signed by the following persons in the capacities indicated, on the
11th day of December, 1998.

<TABLE>
<CAPTION>
         SIGNATURE                                  TITLE
         ---------                                  -----
<S>                                                 <C>


/s/ RICHARD C. EMERY                                President, Chief Executive Officer and
--------------------------------------------        (Principal Executive Officer)
Richard C. Emery                            


/s CHAD GALLOWAY                                    Vice President & Chief Financial Officer
------------------------------------                (Principal Financial Officer)
Chad Galloway


/s/ WILLIAM C. DASHIELL                             Chairman
--------------------------------------------
William C. Dashiell


/s/ DAVID C. BLANKENSHIP                            Director
------------------------------------
David C. Blankenship
</TABLE>



                                      II-3


<PAGE>   155

<TABLE>
<CAPTION>
         SIGNATURE                                  TITLE
         ---------                                  -----
<S>                                                 <C>

/s/ RAND ELLIOTT                                    Director
--------------------------------------------
Rand Elliott


/s/ ROBERT J. GARDNER                               Director
--------------------------------------------
Robert J. Gardner


/s/ ROBERT L. GOLOB                                 Director
--------------------------------------------
Robert L. Golob


/s/ KEITH P. SATTLER                                Director
--------------------------------------------
Keith P. Sattler


/s/ DANN SIMPSON                                    Director
--------------------------------------------
Dann Simpson


/s/ DON SWARTZ                                      Director
--------------------------------------------
Don Swartz


/s/ NORMAN J. TRAAEN                                Director
--------------------------------------------
Norman J. Traaen


/s/ RONALD WACHTER                                  Director
--------------------------------------------
Ronald Wachter
</TABLE>



                                      II-4


<PAGE>   156



                                  EXHIBIT INDEX



<TABLE>
<CAPTION>
Exhibit No.                   Description of Exhibit
-----------                   ----------------------
<S>      <C>                                                                      
 2.1     Agreement and Plan of Merger between USBN and BFC dated as of November
         10, 1998, (included in this Registration Statement as Appendix A to the
         Prospectus/Joint Proxy Statement).

 2.2     Stock Option Agreement between USBN and BFC dated as of November 10,
         1998 (included in this Registration Statement as Appendix D to the
         Prospectus/Joint Proxy Statement).

 5.1     Opinion of Graham & Dunn P.C. as to the legality of securities.

 8.1     Form of Opinion of Graham & Dunn P.C. as to federal income tax
         consequences.

10.1     Employment Agreement of Wes Colley

10.2     Form of NonCompetition Agreement between USBN and Directors of BFC
         and/or the Bank dated as of November 10, 1998.

10.3     Form of Voting Agreement of BFC Directors.

21.1     Subsidiaries of USBN.

23.1     Consent of Graham & Dunn P.C., as to its legality of securities opinion
         (contained in its opinion filed as Exhibit 5.1).

23.2     Consent of Graham & Dunn P.C. as to its tax opinion (contained in its
         opinion filed as Exhibit 8.1).

23.3     Consent of Moss Adams, LLP, USBN's Independent Auditors.

23.4     Consent of McFarland & Alton P.S., USBN's former Independent Auditors.

23.5     Consent of Moss Adams, LLP, BFC's Independent Auditors.

23.6     Consent of Pacific Crest Securities (contained in its opinion described
         at Exhibit 99.1).

23.7     Consent of Columbia Financial Advisors, Inc. (contained in its opinion
         described at Exhibit 99.2).

24.1     Power of Attorney (included in the signature page of this Registration
         Statement) and certified resolutions of the USBN board.

99.1     Opinion of Pacific Crest Securities (included as Appendix B to the
         Prospectus/Joint Proxy Statement).

99.2     Opinion of Columbia Financial Advisors, Inc. (included as Appendix C to
         the Prospectus/Joint Proxy Statement).
</TABLE>



                                      II-5

<PAGE>   157


<TABLE>
<CAPTION>
Exhibit No.               Description of Exhibit
-----------               ----------------------
<S>      <C>                                                                      
99.3     Form of proxy to be mailed to the stockholders of USBN.

99.4     Form of proxy to be mailed to the stockholders of BFC.

99.5     Rule 438 Consent of Wesley Colley.
</TABLE>



                                      II-6