Ameren is a publicly owned company headquartered in St. Louis, US. Founded in 1902, and employing approximately 7,030 individuals, the company operates as an American power and energy holding company. It was formed on December 31, 1997, through the merger of Union Electric Company and Central Illinois Public Service Company (CIPSCO Inc.). Ameren serves 2.4 million electric and 900,000 natural gas customers across 64,000 square miles in central and eastern Missouri and the southern four-fifths of Illinois.
