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.