Edison International, through its subsidiaries, engages in the generation and distribution of electric power. It operates in two segments, Electric Utility and Competitive Power Generation. The Electric Utility segment supplies electricity primarily to residential, commercial, industrial, agricultural, and other customers, as well as public authorities through transmission and distribution networks. Its transmission facilities deliver power from generating sources to the distribution network and consist of lines ranging from 33 kV to 500 kV and substations; and distribution system comprises approximately 59,000 circuit miles of overhead lines, 44,000 circuit miles of underground lines, and 700 distribution substations located in California. The Competitive Power Generation segment is involved in developing, acquiring, owning or leasing, operating, and selling energy and capacity from independent power production facilities. Its operating projects primarily consist of coal-fired and natural gas-fired generating facilities, and renewable energy facilities, primarily wind projects. As of December 31, 2011, this segment owned or leased interests in 43 operating projects with an aggregate net physical capacity of 11,504 megawatts; and had 1 wind project and 1 natural gas-fired peaker plant under construction, totaling net generating capacity of 80 megawatts and 479 megawatts respectively. It also engages in hedging and energy trading activities in power markets, as well as trades in electricity, capacity, fuels, and transmission congestion. Edison International was founded in 1886 and is based in Rosemead, California.