TransCanada PipeLines Limited, a natural gas transmission company with executive offices in Toronto. First incorporated by Act of Parliament on 21 March 1951, TransCanada owns and operates a high pressure natural gas pipeline system extending from Alberta into parts of Québec and into the US. The company is also engaged in the search for, and production of, crude oil and natural gas, and sells natural gas to Canadian and US customers. With the federal government's deregulation of gas prices, the company expanded its marketing operations with its subsidiary Western Gas Marketing Ltd.

In 1988 it made a successful bid for Encor Energy Corp Inc, the largest shareholder of which was debt-plagued Dome Petroleum. In 1995 it had sales or operating revenue of $7.0 billion, assets of $10.3 billion and over 1700 employees. Shares in the company are widely held and foreign ownership stands at 30%. Bell Canada Enterprises Inc owned 49% of the shares. In February 1998 it merged with Nova Corp, creating North America's 4th-largest gas pipeline company.

See also Pipeline Debate.