Ameren Corporation provides electric and gas utility services to more than 2 million electric companies and more than 900,000 natural gas customers. The company operates through subsidiary companies in order to serve customers located within a 64,000-square-mile area of Missouri and Illinois. Ameren s operating companies are AmerenCILCO, AmerenCIPS, AmerenIP and AmerenUE. In addition, the company has several subsidiaries, including AmerenEnergy, a national trading and marketing subsidiary; AmerenEnergy Resources, which focuses on supplying energy solutions to the Midwest market; and Amaren Services, which provides administrative support services to Ameren and its operating companies, subsidiaries and affiliates. Gary L. Rainwater has been the chief executive officer of Ameren for more than two years. He has been with the utility company for over 27 years. Rainwater earned a BS degree from the University of Missouri, and a MS degree from the University of Southern California. Ameren is headquartered in St. Louis.