Alliant Energy Corporation, a utility holding company, provides regulated electricity and natural gas services to residential, commercial, and industrial customers in the Midwest region of the United States. The company, through its subsidiary, Interstate Power and Light Company (IPL), engages in the generation and distribution of electricity, and distribution and transportation of natural gas in Iowa and southern Minnesota; and generation and distribution of steam in Cedar Rapids, Iowa. Alliant Energy, through its subsidiary, Wisconsin Power and Light Company (WPL), is also involved in the generation and distribution of electricity, and distribution and transportation of natural gas in southern and central Wisconsin. As of December, 31, 2011, IPL supplied electricity to 525,770 retail customers and gas to 233,715 retail customers; and WPL supplied electricity to 456,637 retail customers and natural gas to 179,945 retail customers. The company owns a portfolio of coal, natural gas-fired, oil, wind, and hydro power generation facilities; and provides electric utility services to retail customers in food manufacturing, chemical, and paper industries. In addition, it holds investments in various businesses that provide freight transportation services through a short-line railway between Cedar Rapids and Iowa City, Iowa; a barge terminal and hauling services on the Mississippi River; and other transfer and storage services. Further, the company offers renewable energy services, including facility siting, permitting, design, construction, and high voltage connection services for wind and solar projects. Additionally, it owns and leases a non-regulated natural gas-fired energy facility near Sheboygan Falls, Wisconsin; and holds investments in real estate and corporate airplanes businesses. Alliant Energy Corporation was formerly known as Interstate Energy Corp. The company was founded in 1917 and is headquartered in Madison, Wisconsin.