- CEO
- Martin J. Lyons Jr.
- Full Time Employees
- 3,168
- Sector
- Utilities
- Industry
- Regulated Electric
- Address
- 10 Richard Mark Way Collinsville IL United States of America 62234
- IPO Date
- Apr 5, 2010
- Business
- Ameren Illinois Company (AILLO), a subsidiary of Ameren Corporation, operates as a rate-regulated utility providing electric transmission and distribution services along with natural gas distribution to approximately 1.2 million electric customers and over 800,000 natural gas customers across central and southern Illinois, including more than 1,200 communities. The company delivers core services through its Ameren Illinois Electric Distribution, Ameren Illinois Natural Gas, and Ameren Illinois Transmission segments; offers energy efficiency incentives and programs covering lighting, heating, cooling, ventilation, water-saving devices, specialty equipment for industrial, commercial, agricultural, hospitality, data center, and food service applications, weatherization measures, and technical assistance such as retro-commissioning, monitoring-based commissioning, strategic energy management, and process energy advising. Founded in 1902 and headquartered in Collinsville, Illinois, the company, formerly known as Central Illinois Public Service Company until its name change in October 2010, focuses on residential, commercial, and industrial customers in the multi-utility sector. In August 2025, Ameren Illinois received approval from the Illinois Commerce Commission for a $1.6 billion transmission project to construct and upgrade 380 miles of power lines, build three new substations, and enhance existing ones across 13 counties, with construction starting later in 2025 and completion targeted for 2029 to improve energy reliability and accessibility.