Ameren Illinois Company 

Ameren Illinois Company, publicly recognized as Ameren Illinois, functions as a regulated utility, managing the generation, transmission, and distribution of electricity across Illinois. The company also handles natural gas distribution services. It supplies electric power to 1.2 million customers and delivers natural gas to 800,000 customers, collectively covering a substantial 43,700 square-mile territory in central and eastern parts of Illinois. Established in 1902, its headquarters are located in Collinsville, Illinois. The firm was previously known as Central Illinois Public Service Company before rebranding to Ameren Illinois Company in October 2010. It operates as a subsidiary of Ameren Corporation.