<PAGE>

                              FOURTH AMENDMENT TO
                               CREDIT AGREEMENT
                               ----------------

        THIS FOURTH AMENDMENT TO CREDIT AGREEMENT (this "Fourth Amendment") is
dated as of the 29th day of March, 2000 and entered into by and among U.S.
XPRESS ENTERPRISES, INC., a Nevada corporation (the "Borrower"), the BANKS
listed on the signature pages hereof (the "Lenders"), WACHOVIA BANK, N.A., as
Administrative Agent, BANK OF AMERICA, N.A., f/k/a NationsBank, N.A. as
Syndication Agent, FLEET NATIONAL BANK, f/k/a BANKBOSTON, N.A. as Documentation
Agent, and SUNTRUST BANK, successor in interest to SunTrust Bank, Chattanooga,
as Co-Agent (collectively, the "Agents").

                             W I T N E S S E T H:
                             -------------------

        WHEREAS, the parties hereto are parties to that certain Credit
Agreement, dated as of January 15, 1998, as amended by that certain First
Amendment to Credit Agreement dated as of August 11, 1998, as further amended by
that certain Second Amendment to Credit Agreement dated as of August 28, 1998,
and as further amended by that certain Third Amendment to Credit Agreement dated
as of February 22, 2000 (as such Credit Agreement may be amended from time to
time, the "Credit Agreement"); and

        WHEREAS, the Borrower has requested that the Lenders amend the Credit
Agreement to permit certain Investments by the Borrower;

        NOW, THEREFORE, for and in consideration of the above premises and other
good and valuable consideration, the receipt and sufficiency of which hereby is
acknowledged by the parties hereto, the Borrower, the Agents and the Lenders
hereby agree as follows:

        1.  Amendments. Section 6.17 of the Credit Agreement is hereby amended
            ----------
and restated in its entirety as follows:

            Section 6.17. Investments. Neither the Borrower nor any of its
                          -----------
        Subsidiaries shall make Investments in any Person except as permitted by
        Section 6.16 and except Investments in (i) direct obligations of the
        United States Government maturing within one year, (ii) certificates of
        deposit issued by a commercial bank whose credit is satisfactory to the
        Administrative Agent, (iii) commercial paper rated A1 or the equivalent
        thereof by S&P or PI or the equivalent thereof by Moody's and in either
        case maturing within 6 months after the date of acquisition, (iv) tender
        bonds the payment of the principal of and interest on which is fully
        supported by a letter of credit issued by a United States bank whose
        long-term certificates of deposit are rated at least AA or the
        equivalent thereof by S&P and Aa or the equivalent thereof by Moody's,
        (v) acquisitions of the stock of a Person permitted by Section 6.25, or
        (vi) Transplace.com, consisting of cash and certain intangible assets
        (collectively, the "Transplace Investment"), so long as (a) the cash
        portion of the Transplace Investment does not exceed Five Million
        Dollars ($5,000,000), in the aggregate, and (b) the ownership interest
        of Borrower in Transplace.com and the other terms of the Transplace
        Investment are substantially as described by the Borrower to the
        Administrative Agent and to the Banks in written correspondence provided
        by the Borrower, and in conferences held with the Borrower, prior to
        March 29, 2000; provided, however, immediately after giving effect to
                        --------  -------
        the
<PAGE>

        making of any Investment, no Default shall have occurred and be
        continuing.

        2.  Conditions Precedent. This Fourth Amendment and the obligations of
            --------------------
the Lenders evidenced hereunder shall not be effective until the execution and
delivery of this Fourth Amendment by each of the parties hereto and until the
Administrative Agent shall have received a Reaffirmation of Guaranty from each
Subsidiary in substantially the form of Exhibit A-1 hereto.

        3.  Reference to and Effect on the Credit Agreement and the Other Loan
            ------------------------------------------------------------------
            Documents.
            ---------

            (a) On and after the date hereof, each reference in the Credit
Agreement to "this Agreement," "hereunder," "hereof," "herein" or words of like
import referring to the Credit Agreement, and each reference in the other Loan
Documents to the "Credit Agreement," "thereunder," "thereof" or words of like
import referring to the Credit Agreement shall mean and be a reference to the
Credit Agreement as amended hereby.

            (b) Except as specifically amended by this Fourth Amendment, the
Credit Agreement and the other Loan Documents shall remain in full force and
effect and are hereby ratified and confirmed.

            (c) The execution, delivery and performance of this Fourth Amendment
shall not, except as expressly provided herein, constitute a waiver of any
provision of, or operate as a waiver of any right, power or remedy of the
Administrative Agent or any Lender under the Credit Agreement or any of the
other Loan Documents.

        4.  Counterparts. This Fourth Amendment may be executed in any number of
            ------------
counterparts and by different parties hereto in separate counterparts, each of
which when so executed and delivered shall be deemed to be an original and all
of which counterparts, taken together, shall constitute but one and the same
instrument.

        5.  Section References. Section titles and references used in this
            ------------------
Fourth Amendment shall be without substantive meaning or content of any kind
whatsoever and are not a part of the agreements among the parties hereto
evidenced hereby.

        6.  No Default; Reaffirmation of Representations and Warranties. To
            -----------------------------------------------------------
induce the Agents and the Lenders to enter into this Fourth Amendment and to
continue to make advances pursuant to the Credit Agreement, the Borrower hereby
acknowledges and agrees that, as of the date hereof, and after giving effect to
the terms hereof, there exists (i) no Default or Event of Default thereunder,
(ii) no right of offset, defense, counterclaim, claim or objection in favor of
the Borrower arising out of or with respect to any of the loans or other
obligations of the Borrower owed to the Agents and the Lenders under the Credit
Agreement and other Loan Documents, and (iii) all of the representations and
warranties made or deemed to be made under the Credit Agreement are materially
true and correct as of the date of this Fourth Amendment.

        7.  Governing Law. This Fourth Amendment shall be governed by and
            -------------
construed and interpreted in accordance with, the laws of the State of Georgia
without giving effect to any conflict or choice of laws principles.

        8.  Defined Terms. Terms not otherwise defined herein are used herein as
            -------------
defined in the Credit Agreement.
<PAGE>

                                        By:
                                        Title:


                                        FIRST TENNESSEE BANK, N.A.

                                        By:
                                        Title:
<PAGE>

                                  EXHIBIT A-1

                           REAFFIRMATION OF GUARANTY

        THIS REAFFIRMATION OF GUARANTY dated as of March 29, 2000 executed and
delivered by U.S. Xpress, Inc., a Nevada corporation, CSI/Crown, Inc., a Georgia
corporation, JTI, Inc. a Tennessee corporation, Xpress Air, Inc., a Tennessee
corporation, U.S. Xpress Leasing, Inc., a Tennessee corporation, PST Acquisition
Corp., a Nevada corporation, and Victory Express, Inc., a Ohio corporation,
(each a "Guarantor", and collectively, the "Guarantors"), in favor of the
Administrative Agent, for the ratable benefit of the Banks, under the Credit
Agreement referred to below;

        WHEREAS, pursuant to that certain Credit Agreement dated as of January
15, 1998 (as the same may be amended, modified, supplemented or extended from
time to time, the "Credit Agreement") by and among U.S. XPRESS ENTERPRISES,
INC., a Nevada corporation (the "Borrower") and WACHOVIA BANK, N.A., as
Administrative Agent (the "Administrative Agent"), BANK OF AMERICA, N.A. f/k/a
NATIONSBANK, N.A., a Syndication Agent, FLEET NATIONAL BANK f/k/a BANKBOSTON,
N.A., as Documentation Agent, and SUNTRUST BANK, successor in interest to
SunTrust Bank, Chattanooga, as Co-Agent and certain other Banks from time to
time party thereto, the Banks have made available to the Borrower certain
financial accommodations on the terms and conditions set forth in the Credit
Agreement;

        WHEREAS, in connection with the Credit Agreement, each Guarantor
executed and delivered a Guaranty dated as of January 15, 1998 (the "Guaranty")
in favor of the Administrative Agent, providing for each such Guarantor's joint
and several guaranty of repayment of an amount of the indebtedness and
obligations of the Borrowers owing to the Administrative Agent and the Banks
equal to the "Guaranteed Obligations" as that term is defined in the Guaranty;

        WHEREAS, the Borrower, the Banks, and the Administrative Agent have
entered into that certain Fourth Amendment to Credit Agreement dated as of the
date hereof (the "Amendment"), to permit certain Investments by the Borrower;

        WHEREAS, each Guarantor has reviewed the Amendment;

        WHEREAS, it is a condition precedent to the effectiveness of the
Amendment that each Guarantor execute and deliver this Reaffirmation of
Guaranty;

        NOW THEREFORE, for good and valuable consideration, the receipt and
sufficiency of which each Guarantor hereby acknowledges, each Guarantor hereby
agrees as follows:

        Section 1. Reaffirmation. Each Guarantor hereby reaffirms its continuing
obligations to the Administrative Agent and the Banks under the Guaranty and
agrees that neither the transactions contemplated by the Amendment, nor any
future agreements or arrangements whatsoever by the Administrative Agent and the
Banks with the Borrower relating to the Credit Agreement, any of the other Loan
Documents, or any collateral thereunder, shall in any way affect the validity
and enforceability of the Guaranty or reduce, impair or discharge the
obligations of the Guarantor thereunder.
<PAGE>

        Section 2. References. Each Guarantor agrees that each reference to the
Credit Agreement or any of the other Loan Documents shall be deemed to be a
reference to the Credit Agreement or such other Loan Document as amended by the
Amendment, and as each may from time to time be further amended, supplemented,
restated or otherwise modified in the future by one or more other written
amendments or supplemental or modification agreements entered into pursuant to
the applicable provisions of the respective Loan Document.

        Section 3. Defined Terms. Terms not otherwise defined herein are used
herein as defined in the Credit Agreement.

        IN WITNESS WHEREOF, this Reaffirmation of Guaranty is signed, sealed and
delivered as of the date first written above.

U.S. XPRESS, INC.                               U.S. XPRESS LEASING, INC.

By:                                             By:
Title:                                          Title:

CSI/CROWN, INC.                                 PST ACQUISITION CORP.

By:                                             By:
Title:                                          Title:

JTI, INC.                                       VICTORY EXPRESS, INC.

By:                                             By:
Title:                                          Title:

XPRESS AIR, INC.

By:
Title: