TC PipeLines, LP was a publicly traded master limited partnership. TC Energy owned 25.48% of the outstanding units and controlled the general partner. TC PipeLines, LP managed and owned natural gas pipelines in the United States including 46.45% of Great Lakes Gas Transmission Limited Partnership, 50% of Northern Border Pipeline Company, 100% of Gas Transmission Northwest, and 100% of Tuscarora Gas Transmission Company. TC PipeLines, LP was based in Calgary, Alberta.