Alliant Energy is made up of two principal subsidiaries: Interstate Power and Light Company (IPL) and Wisconsin Power and Light Company (WPL).
IPL was created in 1925 by the merger of many small utility companies in Iowa and Minnesota. In the decade following the merger the company expanded into Wisconsin, North and South Dakota, Nebraska, Oklahoma, and Manitoba, Canada.
Today the company is named Alliant Energy and provides electricity to about 1 million customers and natural gas to 415,000 across four states. The company produces electricity at 34 power plants with a total generating capacity of 4,900 MW.
Alliant Energy is publicly traded on the New York Stock Exchange under the ticker symbol LNT, is a member of the S&P 400, is #687 in the Fortune 1000, has 3.945 employees, and had $3.38 billion in revenue in 2013.