TransCanada Corporation is an energy infrastructure company. The Company is engaged in the development and operation of North American energy infrastructure, including natural gas and liquids pipelines, power generation and natural gas storage facilities. Its segments include Canadian Natural Gas Pipelines, U.S. Natural Gas Pipelines, Mexico Natural Gas Pipelines, Liquids Pipelines and Energy. The Company operates in three businesses: Natural Gas Pipelines, Liquids Pipelines and Energy. The Natural Gas Pipelines and Liquids Pipelines segments principally consist of its respective natural gas and liquids pipelines in Canada, the United States and Mexico, as well as its regulated natural gas storage operations in the United States. The Energy segment includes its power operations and the non-regulated natural gas storage business in Canada. TransCanada PipeLines Limited (TCPL) is its principal operating subsidiary.