continental daily natural gas demand through 91,900 km (57,100 mi) of pipelines. In addition, the company owns 535 Bcf of natural gas storage facilities, making TC Energy one of the largest natural gas storage providers in North America. This segment is TC Energy's largest segment, generating approximately two-thirds of the company's EBITDA in 2017. The Natural Gas Pipelines business is split into three operating segments: Canadian Natural Gas Pipelines, U.S. Natural Gas Pipelines, and Mexico Natural Gas Pipelines. The major pipeline systems include: NGTL System (24,320 km) A wholly owned subsidiary, NOVA Gas Transmission Ltd., connects gas producers in the Western Canadian Sedimentary Basin with consumers and exports. TC Energy has the largest and most extensive natural gas network in Alberta. Canadian Mainline (14,077 km) this pipeline serves as a long haul delivery system transporting natural gas from the Western Canadian Sedimentary Basin across Canada to Ontario and Québec to deliver gas to downstream Canadian and U.S. markets. The pipeline has evolved accommodate additional supply connections closer to its markets. The mainline is over 60 years old Columbia Gas (18,113 km) This natural gas transportation system serves the Appalachian Basin, which contains the Marcellus and Utica plays, two of the largest natural gas shale plays in North America. The system also interconnects with other pipelines that provide access to the U.S. Northeast and the Gulf of Mexico. ANR Pipeline System (15,109 km) This pipeline system connects supply basins and markets throughout the U.S. Midwest, and south to the Gulf of Mexico. This includes connecting supply in Texas, Oklahoma, the Appalachian Basin and the Gulf of Mexico to markets in Wisconsin, Michigan, Illinois and Ohio. In addition, ANR has bi-directional capability on its Southeast Mainline and delivers gas produced from the Appalachian basin to customers throughout the Gulf Coast Region.Columbia Gulf (5,377 km) – This pipeline system was originally designed as a long haul delivery system transporting supply from the Gulf of Mexico to major demand markets in the U.S. Northeast. The pipeline is now transitioning to a north-to-south flow and expanding to accommodate new supply in the Appalachian Basin and its interconnects with Columbia Gas and other pipelines to deliver gas to various Gulf Coast markets.Mexico Pipeline Network (1,680 km) – This consists of a growing network of natural gas pipelines in Mexico. Projects in development include:Coastal GasLink Pipeline Project – In June 2012 it was announced that TransCanada was