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): August 24, 2004 TC PIPELINES, LP (Exact name of registrant as specified in its charter) DELAWARE 000-26091 52-2135448 (State or other jurisdiction of (Commission (IRS Employer incorporation) File Number) Identification No.) 110 TURNPIKE ROAD, SUITE 203 WESTBOROUGH, MASSACHUSETTS 01581 (Address of principal executive offices) (Zip Code) Registrant's telephone number, including area code: (508) 871-7046 NOT APPLICABLE (Former name or former address, if changed since last report.) Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions: [ ] Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425) [ ] Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12) [ ] Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b)) [ ] Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))

ITEM 7.01 REGULATION FD DISCLOSURE. TC PipeLines, LP owns a 30% general partner interest in Northern Border Pipeline Company ("Northern Border Pipeline"). 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 August 24, 2004, Northern Border Pipeline issued a press release, which is attached as Exhibit 99.1 announcing that in response to its posting of firm transportation capacity available on its pipeline system on November 1, 2004, it has received binding commitments from several companies for an aggregate of 431 million cubic feet per day of transportation capacity, predominantly for terms of five to six months. The information in Item 7.01 of this report is being furnished, not filed, pursuant to Regulation FD. Accordingly, the information in Item 7.01 of this report will not be incorporated by reference into any registration statement filed by the Partnership under the Securities Act of 1933, as amended, unless specifically identified therein as being incorporated therein by reference. ITEM 9.01 FINANCIAL STATEMENTS AND EXHIBITS. (c) Exhibits. 99.1 Northern Border Pipeline Company's News Release dated August 24, 2004.

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 Date: August 24, 2004 By: /s/ RONALD J. TURNER ------------------------------------- Ronald J. Turner President and Chief Executive Officer

Exhibit 99.1 [NORTHERN BORDER PIPELINE COMPANY LOGO] NEWS RELEASE 13710 FNB Parkway Omaha, NE 68154-5200 For Further Information Contact: Media Contact: Martha Sumner-Kenney (402) 492-3401 Investor Contacts: Ellen Konsdorf Lisa Couillard (877) 208-7318 NORTHERN BORDER PIPELINE COMPANY ANNOUNCES SIGNIFICANT CAPACITY COMMITMENTS FOR IMMEDIATE RELEASE: TUESDAY, AUGUST 24, 2004 OMAHA - (NYSE: NBP; NASDAQ: TCLP) - Northern Border Pipeline Company announced today that in response to its posting of firm transportation capacity available on its pipeline system on November 1, 2004, it has received binding commitments from several companies for an aggregate of 431 million cubic feet per day (MMcf/d) of transportation capacity. The commitments are at the maximum rate available under the pipeline's tariff, predominantly for terms of five to six months. These new commitments are in addition to the 140 MMcf/d that was recontracted earlier this year for terms of one year or greater. Approximately 7% of the pipeline's system capacity remains available beginning November 1, 2004. The company will continue to market the available capacity in accordance with its tariff. Northern Border Pipeline Company is a general partnership that owns and operates a 1,249-mile interstate pipeline that transported approximately 22 percent of all Canadian gas imported into the United States in 2003. Northern Border Partners, L.P. (NYSE:NBP) owns a 70 percent general partner interest in Northern Border Pipeline Company. The remaining 30 percent general partner interest is owned by TC PipeLines, LP (Nasdaq: TCLP). THIS PRESS RELEASE CONTAINS FORWARD-LOOKING STATEMENTS AS DEFINED BY FEDERAL LAW. ALTHOUGH THE COMPANY BELIEVES ANY SUCH STATEMENTS ARE BASED ON REASONABLE ASSUMPTIONS, THERE IS NO ASSURANCE THAT ACTUAL OUTCOMES WILL NOT BE MATERIALLY DIFFERENT. ADDITIONAL INFORMATION ABOUT ISSUES THAT COULD LEAD TO MATERIAL CHANGES IN PERFORMANCE IS CONTAINED IN THE COMPANY'S FILINGS WITH THE SECURITIES AND EXCHANGE COMMISSION. #####