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.

For more than a century, AmerenCIPS, AmerenCILCO, AmerenIP and their predecessors have proudly delivered the energy that powers our communities. October 1, 2010 marked the next step in our evolution, as the three Illinois utilities merged into a single operating company - Ameren Illinois - based in Peoria, Illinois.

Our roots in Illinois date back to the early 1900's. You can count on our commitment to safety, service and energy efficiency. While we’re busy keeping the energy flowing, we’re also looking forward.