TC Pipelines LP is a publicly traded Delaware limited partnership formed in 1998 by TransCanada Corporation and its subsidiaries to acquire own and participate in the management of energy infrastructure businesses in North America. The Company is managed by its general partner, TC PipeLines GP, Inc. which is an indirect, wholly-owned subsidiary of TransCanada. Through its pipeline systems, the Company transports natural gas in the United States. The Company has equity ownership interests in four natural gas interstate pipeline systems that are accounted for on an equity basis and two wholly-owned pipelines that are accounted for on a consolidated basis. Collectively, they are designed to transport approximately 8.9 billion cubic feet per day of natural gas from producing regions and import facilities to market hubs and consuming markets mainly in the Western and Midwestern U.S.. All of its pipeline systems are operated by subsidiaries of TransCanada. The Company's customers are large utilities, local distribution companies and natural gas marketers and producing companies. The Company's pipelines generate revenue by charging rates for transporting natural gas. The majority of its pipeline systems' natural gas transportation services are provided through firm service transportation contracts with a reservation or demand charge which reserves pipeline capacity, regardless of use, for the term of the contract. Through its disciplined investment philosophy, the Company now has investments in six critical FERC regulated, low-risk energy infrastructure pipelines. The Company's pipelines are subject to stringent and complex federal, state, and local laws and regulations governing environmental protection, including air emissions, water quality, wastewater discharges and solid waste management.