EXHIBIT 10.21
           
           Northern Border Pipeline Company
                      Agreement


Further to the Letter Agreement dated September 4, 1996
between TransCanada PipeLines Limited, Northern Plains
Natural Gas Company, Pan Border Gas Company and Northwest
Border Pipeline Company (the "Letter Agreement") and in
consideration of the covenants and agreements contained
herein each of the undersigned agrees as follows:

1.   Cash Payment

Concurrently with the closing of an initial public offering
of common units (the "IPO") by TC PipeLines, LP, a master
limited partnership ("TC PipeLines") formed by TransCan
Northern Ltd. and TransCanada Border PipeLine Ltd. (the
"TransCanada Participants"), the TransCanada Participants
agree to make a cash payment of $11 million (U.S.) to
Northern Plains Natural Gas Company, Pan Border Gas Company
and Northwest Border Pipeline Company (the "Enron/Williams
Participants").  This payment is the same amount that was
paid to the TransCanada Participants in 1993 in
consideration for their agreement to permit the
Enron/Williams Participants to form Northern Border
Partners, L.P. (Northern Border Partners) and to offer
interests therein to the public. The payment shall be
allocated as follows:

<TABLE>
<CAPTION>
                                          %       U.S. $

  <S>                                   <C>     <C>
  Northern Plains Natural Gas Company    50.0    5,500,000
  Pan Border Gas Company                 32.5    3,575,000
  Northwest Border Pipeline Company      17.5    1,925,000
                                        100.0   11,000,000
</TABLE>
                                     
2.   Amendment of Partnership Agreement

The TransCanada Participants and Northern Border
Intermediate Limited Partnership ("NBILP") agree to amend
Sections 1, 8.2.1 and 8.2.5 of the General Partnership
Agreement (the "Partnership Agreement") of Northern Border
Pipeline Company (the "Partnership") to give effect to the
change in ownership of general partner interests in the
Partnership from the TransCanada Participants to TC
PipeLines or any of its subsidiaries as contemplated in the
prospectus filed on December 30, 1998 (the "IPO Prospectus")
with the Securities and Exchange Commission (the "SEC") and
to amend Section 10.6 to provide reciprocal rights to NBILP
with respect to a transfer of the general partner interest
in the TransCanada Participants' transferee.  Further, the
TransCanada Participants and NBILP agree to amend the
Partnership Agreement to add the following provision:
     
9.3  Business Opportunities.  The Partners and their
     Affiliates are free to pursue any business opportunity
     without first offering such business opportunity to the
     Partnership (and such pursuit shall not be a breach of any
     duty to the Partnership or to any other partner), except
     that no Partner and no Affiliate of a Partner may pursue the
     project known as Project 2000 filed with the Federal Energy
     Regulatory Commission in Docket No. CP99-21 or any business
     opportunity that consists of an expansion, addition,
     betterment, improvement, renewal or replacement of the Line
     as it exists on January 15, 1999 (the "Effective Date")
     unless the party desiring to pursue such opportunity first
     offers to the Partnership the opportunity to pursue such
     business opportunity and the Partnership declines to do so.
     The terms "expansion, addition, betterment, improvement,
     renewal or replacement" shall not include any extension of
     the Line beyond its terminus as it exits on the Effective
     Date or the construction or acquisition of any pipeline
     (including any lateral or any other extension) that connects
     with the Line as it exists on the Effective Date.  The
     parties hereto agree that the waivers and agreements in this
     Section 9.3 constitute an agreement among the partners of
     the Partnership that governs the management of the business
     and affairs of the Partnership and the relationship among
     the partners and the Partnership, as contemplated by Article
     6132b-1.03 of the Texas Revised Partnership Act.  The
     parties hereto further agree that the waivers and agreements
     in this Section 9.3 identify certain types and categories of
     activities which do not violate the duty of loyalty to the
     Partnership, and that such (types and categories) are not
     manifestly unreasonable.
     
3.   Northern Border Partners and TC PipeLines Document Review

Northern Border Partners and TC PipeLines shall each be
given a reasonable opportunity to review documents which are
prepared by the other for public disclosure but only with
respect to information regarding the Partnership.  The
Northern Border Partners' and TC PipeLines' review is to be
conducted on a reasonable, prompt and timely basis.

4.   Transfer of TransCanada Participants Partnership Interest

By the execution of this Agreement, NBILP and the members of
the Management Committee of the Partnership, conditioned
upon there being no material changes to the structure and
purpose of TC PipeLines as described in the IPO Prospectus,
formally consent and approve upon the closing of the IPO by
TC PipeLines (i) the transfer of the partnership interests
owned by the TransCanada Participants to TC PipeLines and/or
to a subsidiary thereof; and (ii) the admission of TC
PipeLines, or a subsidiary thereof, as a general partner in
the Partnership.  To the extent that the public and private
offerings and sales of units in TC PipeLines (including
offerings and sales of units occurring subsequent to the IPO
and sale of said units) constitute a transfer of an
ownership in the Partnership, NBILP and the members of the
Management Committee of the Partnership consent to that
transfer.  Each of the undersigned (other than the
TransCanada Participants) further agrees to promptly take
all other actions within its control as may be reasonably
requested by the TransCanada Participants to implement the
purposes of this paragraph.

5.   Access to Records

The TransCanada Participants, the underwriters or placement
agents for the IPO or any subsequent issuances and sales of
securities by TC PipeLines and/or its subsidiaries and their
respective employees, agents, attorneys, auditors, and
consultants (collectively, the "Working Group") shall be
given access, which is reasonable and not disruptive to the
ongoing business, to knowledgeable representatives of the
Partnership and Northern Plains Natural Gas Company, as
Operator,  in connection with their due diligence efforts
with respect to the IPO prospectus, periodic disclosure
documents and future offering documents of TC PipeLines.
The Partnership shall provide assistance to the Working
Group in obtaining (x) the consent of the Partnership's
independent public accountants to the inclusion of their
audit report in any document or report that may be filed
with the SEC, and (y) a customary comfort letter from such
accountants with respect to the Partnership financial
information.  The Partnership shall also provide to the
Working Group in a timely fashion financial and operating
data including financial statements, projections (which are
customarily prepared by or for the Partnership) and other
information and documents regarding the Partnership as may
be necessary or reasonably appropriate for compliance by TC
PipeLines and its affiliates with accounting rules or
securities law requirements in the United States and Canada
with respect to the IPO prospectus, periodic disclosure
documents and future offering documents of TC PipeLines as
well as any applicable United States or Canadian tax
requirements.  The TransCanada Participants agree that any
projections provided pursuant to this section will not be
disclosed except if such projections are required to be
given by a specific SEC form, instruction, comment or
request.  The TransCanada Participants shall bear any costs
and expenses incurred to convey information in excess of the
information currently provided to the TransCanada
Participants as a general partner of the Partnership.

6.   Filings
The Partnership and Northern Plains Natural Gas Company,
upon determining that an event has occurred which is
material to the business and affairs of the Partnership,
shall promptly notify TC PipeLines and Northern Border
Partners of such event provided, however, that the
Partnership and Northern Plains Natural Gas Company may keep
material information confidential for limited periods of
time and for proper Partnership purposes.  TC PipeLines and
Northern Border Partners agree to consult with the other
before issuing any press release or otherwise making public
statements with respect to the business, operations,
financial condition, operating results and prospects of the
Partnership or before making any filings with any federal,
state or local regulatory agency or any securities exchange
which contains statements with regard thereto.  TC PipeLines
and Northern Border Partners shall use their best efforts to
provide to the other a reasonable opportunity to review and
comment upon any such proposed press release, public
statement, or filing prior to release thereof; provided,
however, that nothing in this Agreement shall prohibit TC
PipeLines and Northern Border Partners from issuing any
press release or making any public statement or making any
filing required by law.  To the extent practicable, press
releases, public statements or filings will be coordinated
so that information regarding the Partnership is released,
made and published simultaneously.

7.   If the offering contemplated in the IPO Prospectus does
not close for any reason the parties hereto that are parties
to the Letter Agreement acknowledge and agree that the
Letter Agreement shall be operative and remain binding and
effective, otherwise, it shall become null and void.

8.   This Agreement may be executed and delivered in
counterparts and by facsimile and, if so executed and
delivered by such means, the execution and delivery of a
counterpart or facsimile by each of the parties hereto shall
constitute execution and delivery of this Agreement.


     Executed this 17th day of March, 1999.

Enron/ Williams Participants

Northern Plains Natural Gas Company

By: Jerry L. Peters

Pan Border Gas Company

By: Stanley C. Horton

Northwest Border Pipeline Company

By: Brian E. O'Neill

TransCanada Participants

TransCanada Border PipeLine Ltd.

By: John W. Carruthers

By: Paul F. MacGregor

TransCan Northern Ltd.

By: John W. Carruthers

By: Paul F. MacGregor

Northern Border Pipeline Company By each of its Partners

Northern Border Intermediate Limited Partnership

By: Larry L. DeRoin

TransCanada Border PipeLine Ltd.
By: John W. Carruthers

By: Paul F. MacGregor

TransCan Northern Ltd.
By: John W. Carruthers

By: Paul F. MacGregor

Northern Border Partners

Northern Border Partners, L.P.

By: Larry L. DeRoin

Management Committee Members of Northern Border Pipeline
Company

/s/Brian E. O'Neill
Brian E. O'Neill


/s/Stanley C. Horton
Stanley C. Horton


/s/Larry L. DeRoin
Larry L. DeRoin


/s/John W. Carruthers
John W. Carruthers

Northern Plains Natural Gas Company (As Operator)

By: Jerry L. Peters