Ameren Illinois, Our History 
Ameren was created by the December 1997 merger of CIPSCO Incorporated (parent company of Central Illinois Public Service which became know as AmerenCIPS) and Union Electric Company. In 2003 Ameren grew with the acquisition of CILCORP, Inc., parent of Central Illinois Light Company, which became known as AmerenCILCO, and in 2004 Ameren acquired Illinois Power Company - which became AmerenIP. In October 2010 AmerenCIPS, AmerenCILCO and AmerenIP officially merged to become Ameren Illinois.

Ameren Illinois is a regulated electric and gas delivery company based in Collinsville, Illinois. Our parent company is Ameren Corporation located in St. Louis, Missouri. As a delivery company, Ameren Illinois is in the business of energy distribution. All customers can choose their electric supplier, and non-residential customers can choose their gas supplier.

Our roots in Illinois date back to the early 1900's. You can count on our commitment to safety, service and energy efficiency.

Linemen working on transformer, keeping the power flowing. 
To keep the power flowing, Ameren Illinois maintains 4,500 miles of transmission lines and 45,400 miles of distribution lines.
Ameren Illinois natural gas workers keeping the gas flowing. 
To keep the gas flowing, Ameren Illinois maintains natural-gas transmission and distribution mains and underground natural gas storage fields.
Ameren Illinois, Our history, history of Ameren Illinois, who we are Ameren Illinois, all about us Ameren Illinois
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