Union Electric Company, doing business as Ameren Missouri, engages in the rate-regulated electric generation, transmission, and distribution business in Missouri. It generates electricity through coal, nuclear, natural gas, hydroelectric, methane gas, and solar energy sources. The company is also involved in the rate-regulated natural gas distribution business. It supplies electric services to 1.2 million customers and natural gas services to 0.1 million customers in a 24,000 square-mile area in central and eastern Missouri. The company was founded in 1881 and is headquartered in St. Louis, Missouri. Union Electric Company operates as a subsidiary of Ameren Corporation.