Exhibit 21.1

SUBSIDIARIES OF THE REGISTRANT

1.	The Registrant holds a 98.9899 per cent limited partner interest inTC GL Intermediate Limited Partnership, a Delaware limited partnership.
2.	Through its interest in TC GL Intermediate Limited Partnership, the Registrant holds a 46.45 per cent general partner interest in Great Lakes Gas Transmission Limited Partnership, a Delaware limited partnership.
3.	The Registrant holds a 98.9899 per cent limited partner interest in TC PipeLines Intermediate Limited Partnership, a Delaware limited partnership.
4.	Through its interest in TC PipeLines Intermediate Limited Partnership, the Registrant holds a 50 per cent general partner interest in Northern Border Pipeline Company, a Texas general partnership.
5.	Through its interest in TC PipeLines Intermediate Limited Partnership, the Registrant wholly-owns North Baja Pipeline, LLC, a Delaware limited liability company.
6.	The Registrant holds a 98.9899 per cent limited partner interest in TC Tuscarora Intermediate Limited Partnership, a Delaware limited partnership.
7.	Through its interest in TC Tuscarora Intermediate Limited Partnership, the Registrant wholly-owns TC Pipelines Tuscarora LLC, a Delaware limited liability company.
8.	Through its interest in TC Tuscarora Intermediate Limited Partnership and TC Pipelines Tuscarora LLC, the Registrant wholly-owns Tuscarora Gas Transmission Company, a Nevada general partnership.