8-K

                                  UNITED STATES
                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549

                                    FORM 8-K



                                 CURRENT REPORT
                       Pursuant to Section 13 or 15(d) of
                       the Securities Exchange Act of 1934

         Date of Report (Date of earliest event reported): MAY 21, 2004



                                TC PIPELINES, LP
             (Exact name of registrant as specified in its charter)



           DELAWARE                     000-26091                 52-2135448
(State or other jurisdiction           (Commission             (I.R.S. Employer
     of incorporation)                 File Number)           Identification No.



     110 TURNPIKE ROAD, SUITE 203                                  01581
      WESTBOROUGH, MASSACHUSETTS                                 (Zip Code)
(Address of principal executive offices)



                                 (508) 871-7046
              (Registrant's telephone number, including area code)





ITEM 5.  OTHER EVENTS AND REGULATION FD DISCLOSURE

TC PipeLines, LP owns a 30% general partner interest in Northern Border Pipeline
Company. The remaining 70% is owned by Northern Border Partners, L.P. ("Northern
Border Partners"), a publicly traded limited partnership controlled by
affiliates of Enron Corp. ("Enron"). Two of Northern Border Partners' general
partners, Northern Plains Natural Gas Company and Pan Border Gas Company, are
owned by CrossCountry Energy, LLC, a wholly-owned subsidiary of Enron.

On May 21, 2004, Northern Border Partners issued a press release, which is
attached as Exhibit 99.1 and incorporated by reference herein, announcing the
potential sale of CrossCountry Energy, LLC, and, as a result, potential change
in general partner ownership of Northern Border Partners.


ITEM 7.  FINANCIAL STATEMENTS AND EXHIBITS

     (c) Exhibits

     99.1  Northern Border Partners, L.P. Press Release dated May 21, 2004.


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                                   SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the
registrant has duly caused this report to be signed on its behalf by the
undersigned hereunto duly authorized.

                                           TC PipeLines, LP

                                    By: TC PipeLines GP, Inc.,
                                        its general partner

Dated: May 21, 2004                 By: /s/ AMY W. LEONG
                                        ---------------------------------
                                        Amy W. Leong
                                        Controller


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                                  EXHIBIT INDEX



EXHIBIT          DESCRIPTION
- -------          -----------
              
99.1             Northern Border Partners, L.P. Press Release, dated
                 May 21, 2004



                                      - 4 -

EX-99.1

                                                                    EXHIBIT 99.1

[COMPANY LOGO]  NORTHERN BORDER            News             13710 FNB Parkway
                PARTNERS, L.P.             Release          Omaha, NE 68154-5200

                                           For Further Information
                                           Contact:

                                           Media Contact:
                                           Beth Jensen
                                           (402) 492-3400

                                           Investor Contact:
                                           Ellen Konsdorf
                                           Lisa Couillard
                                           (877) 208-7318


NORTHERN BORDER PARTNERS, L.P. ANNOUNCES
POTENTIAL CHANGE IN GENERAL PARTNER OWNERSHIP

FOR IMMEDIATE RELEASE:  FRIDAY, MAY 21, 2004

     OMAHA - Northern Border Partners, L.P. (NYSE - NBP) has been advised that
Enron Corp. reached an agreement to sell CrossCountry Energy, LLC, which
includes general partner interests in Northern Border Partners, to NuCoastal
LLC, whose owners are affiliates of Kelso & Company, ArcLight Capital Partners
LLC, Citigroup, and Oscar S. Wyatt, Jr. The sale to NuCoastal has been approved
by Enron's Board of Directors and is supported by the Official Unsecured
Creditors' Committee.

     The transaction also requires the approval of the Bankruptcy Court, which
will oversee an "overbid" process to give other potential buyers an opportunity
to submit superior bids. Allowing for the "overbid" process, as well as
Bankruptcy Court, certain regulatory and governmental approvals, Enron is
targeting a close by the fourth quarter of 2004.

     CrossCountry Energy, a wholly-owned subsidiary of Enron, holds interests in
three major North American gas pipeline businesses. CrossCountry's general
partnership interests in Northern Border Partners are held through Northern
Plains Natural Gas Company and Pan Border Gas Company. CrossCountry also owns
NBP Services Corporation, which provides administrative services to the
partnership.


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Additional details of the sale including Enron's press release can
be found at www.enron.com.

     As a result of the transaction, NuCoastal would effectively own 1.65
percent of the aggregate 2 percent general partnership interest in Northern
Border Partners. Therefore, NuCoastal would be entitled to an 82.5 percent vote
on the Partnership Policy Committee of Northern Border Partners. An affiliate of
TransCanada PipeLines Limited owns the remaining general partner interest and is
entitled to an aggregate 17.5 percent vote on the Partnership Policy Committee.
The limited partnership interests in Northern Border Partners are nearly all
held by the public.

     Northern Border Partners, L.P. is a publicly traded partnership formed to
own, operate and acquire a diversified portfolio of energy assets. The
Partnership owns and manages natural gas pipelines and is engaged in the
gathering and processing of natural gas. More information may be found at
http://www.northernborderpartners.com.



THIS PRESS RELEASE INCLUDES FORWARD-LOOKING STATEMENTS WITHIN THE MEANING OF
SECTION 27A OF THE SECURITIES ACT OF 1933 AND SECTION 21E OF THE SECURITIES
EXCHANGE ACT OF 1934. ALTHOUGH NORTHERN BORDER PARTNERS, L.P. BELIEVES THAT
ENRON'S EXPECTATIONS ARE BASED ON REASONABLE ASSUMPTIONS, THERE IS NO ASSURANCE
THAT SUCH EXPECTATIONS WILL BE ACHIEVED. IMPORTANT FACTORS THAT COULD CAUSE
ACTUAL RESULTS TO DIFFER MATERIALLY FROM THOSE IN THE FORWARD-LOOKING STATEMENTS
INCLUDE DEVELOPMENTS IN ENRON'S VOLUNTARY PETITION FOR BANKRUPTCY INCLUDING
BANKRUPTCY COURT APPROVAL OF THE SALE OF CROSSCOUNTRY ENERGY AND OUTCOME OF
ENRON'S CHAPTER 11 PROCESS; AND THE SUCCESS IN OBTAINING ALL NECESSARY
REGULATORY AND GOVERNMENTAL APPROVALS.


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