History of Ameren in Timeline

Ameren Corporation is an American power company formed in 1997 through the merger of Union Electric Company and Central Illinois Public Service Company. Headquartered in St. Louis, it serves 2.4 million electricity and 900,000 natural gas customers across a 64,000-square-mile area in Missouri and Illinois. As a holding company, Ameren oversees multiple power and energy companies, providing essential services to a significant portion of the Midwest.

1921: CILCO Dividend

Since 1921 CILCO had been paying a dividend.

1929: Bagnell Dam Completion

In 1929, the Bagnell Dam was completed on the Osage River, generating nearly 175 megawatts of hydroelectricity for Missouri's Union Electric Company. The dam also created the Lake of the Ozarks.

1931: Union Electric Buys Power from Keokuk Dam

In 1931, Union Electric Light and Power began buying power from the Keokuk, IA dam, and later bought the dam. This provided 134 megawatts of hydroelectricity over a record-breaking distance.

1947: Illinois Power Dividends

Since 1947, Illinois Power Company had been paying dividends.

1952: Midwest Power Pool System Formation

In 1952, Central Illinois Public Service Company became a major pooled energy power distributor with Union Electric Company, forming the Midwest Power Pool system.

1963: Taum Sauk Plant Construction Completed

In 1963, Union Electric completed construction of the 350-megawatt Taum Sauk Plant in Reynolds County, Missouri.

1984: Callaway Nuclear Generating Station Begins Operation

In 1984, Union Electric added nuclear energy to its power generation mix with the Callaway Nuclear Generating Station, providing 1,143 megawatts of power from Callaway County, Missouri.

1991: Illinois Power Reorganizes as Illinova Corporation

In 1991, Illinois Power reorganized as a holding company, Illinova Corporation.

1994: NGC Corporation

Around 1994, NGC Corporation had been an integrated natural gas services company.

1995: Shareholders Approve Merger

In 1995, shareholders of CIPSCO Inc. and Union Electric Company approved the merger of the two companies to form Ameren Corporation.

1996: CILCO Growth

By 1996, CILCO had grown to over US$150 million in assets, and carried US$330 million in long-term debt.

December 31, 1997: Ameren Corporation Merger

On December 31, 1997, Ameren Corporation was created through the merger of Union Electric Company of St. Louis, Missouri, and Central Illinois Public Service Company of Springfield, Illinois.

June 1998: Dynegy Inc. Creation

In June 1998, Dynegy Inc. was created from the merger of Chevron's natural gas and natural gas liquids businesses with Dynegy's predecessor, NGC Corp.

1999: Study links deaths to air pollution from Labadie plant

A study published in the journal Science used Medicare records to estimate deaths tied to air pollution from coal plants. The study estimated that from 1999 to 2020, approximately 4,000 deaths were linked to “fine particulate matter” from Labadie, far more than any other coal plant across seven Midwestern states.

February 1, 2000: Illinova Merges with Dynegy

On February 1, 2000, Illinova became a wholly owned subsidiary of Dynegy Inc.

2000: AmerenEnergy Resources Formed

In 2000, Ameren formed the holding company AmerenEnergy Resources, including the subsidiaries AmerenEnergy Marketing and AmerenEnergy Generating.

2002: Voluntary Retirement Program Announced

In 2002, Ameren Corporation announced a voluntary retirement program offered to approximately 1,000 of its 7,400 employees.

2003: Charles Mueller Retirement

At the end of 2003, Ameren's chairman and chief executive, Charles Mueller, retired and was succeeded by Gary Rainwater.

2003: Ameren Acquires CILCORP

In 2003, Ameren acquired Peoria-based CILCORP, Inc. and its subsidiary, Central Illinois Light Company (CILCO), from AES Corporation.

December 2004: Patrick T. Stokes Elected to Board of Directors

In December 2004, Patrick T. Stokes, the president and CEO of Anheuser-Busch Cos., Inc., was elected to the Ameren board of directors.

2004: Ameren Acquires Illinois Power Company

In 2004, Ameren acquired Illinois Power Company from Dynegy Inc., marking Ameren as the major investor-owned power company in downstate Illinois.

December 14, 2005: Taum Sauk Plant Failure

On December 14, 2005, the Taum Sauk pumped storage plant failed, causing extensive damage. Consequently, FERC fined Ameren $15 million.

2007: Rush Island Modifications

From 2007 through 2010 Ameren made major modifications at the Rush Island Plant

2009: Wind Power Purchase Agreement

In 2009, AmerenUE signed an agreement to purchase 102 megawatts of wind power from the Pioneer Prairie Wind Farm in Iowa.

2009: Construction of Ameren UE Tower

In 2009, the Ameren UE Tower, a 106.5-meter lattice steel structure combining an electricity pylon and a radio tower, was built near Ameren's headquarters in St. Louis, Missouri. It carries two 138 kV circuits.

April 21, 2010: Taum Sauk Plant Resumes Operation

On April 21, 2010, the 450-megawatt Taum Sauk pumped storage hydroelectric plant began generating electricity again after reconstruction.

October 1, 2010: Illinois Operating Companies Merger

On October 1, 2010, Ameren's three Illinois operating companies merged to become Ameren Illinois Company, and AmerenUE changed its name to Ameren Missouri Company.

2010: Rush Island Modifications

From 2007 through 2010 Ameren made major modifications at the Rush Island Plant

2010: Renewable capacity

In 2010, AmerenUE committed to add 100 megawatts of renewable capacity to serve its Missouri customers.

2010: Service in Illinois Ends

In 2010, AmerenUE served adjoining parts of Illinois until this year.

2010: EPA notice of Clean Air Act violations for Labadie

In 2010, Labadie received a notice of Clean Air Act violations from the EPA for “major modifications that caused a significant net emissions increase” without obtaining proper permits.

2011: EPA notice of Clean Air Act violations for Labadie

In 2011, Labadie received a notice of Clean Air Act violations from the EPA for “major modifications that caused a significant net emissions increase” without obtaining proper permits.

2011: EPA Lawsuit Filed

In 2011, the United States Environmental Protection Agency (EPA) filed suit against Ameren Missouri concerning excess sulfur (SO2) emissions from the Rush Island Plant.

June 2014: Soil Remediation Begins

In June 2014, Ameren began removing contaminated soil from the site of a former coal gasification plant in Columbia, Missouri.

September 2014: Expected Completion of Soil Remediation

In June 2014, Ameren expected to finish removing contaminated soil from the site of a former coal gasification plant in Columbia, Missouri by September 2014.

2015: Innovation Center Opening

In 2015, Ameren became the first major energy company to open an Innovation Center at the Research Park, University of Illinois at Urbana-Champaign.

2016: Pilot Program Rejected

In 2016, Ameren attempted to launch a pilot program to install electric vehicle charging stations, but state utility regulators turned down oversight of the project.

2016: Recognition as a Top Energy Company to Work For

In 2016, Ameren was named 10th on Business Insider’s list of the 10 best energy companies to work for in America.

January 2017: District Court Ruling on Clean Air Act Violation

In January 2017, the District Court found that Ameren violated the Clean Air Act. A remedy was ordered to equip its Rush Island coal plant in Jefferson County, Missouri, with scrubbers.

2017: Institutional Investors

As of 2017 Ameren shares are mainly held by institutional investors (Vanguard group, BlackRock, State Street Corporation, among others).

2017: United States v. Ameren Missouri

United States v. Ameren Missouri, 229 F.Supp.3d 906 (2017) 48295 (D.C., E.D. Missouri, Eastern Division. 01/23/17).

2018: "Charge Ahead" Program Launched

In early 2018, Ameren launched a program called "Charge Ahead" which incentivizes the installation of around 1,200 charging stations and adoption of commercial electric vehicles.

2019: City Considers Purchasing Lot

As of 2019 the city is considering purchasing the lot to create a public park.

2020: Study links deaths to air pollution from Labadie plant

2021: Service Area

As of 2021, Ameren Illinois and Ameren Missouri distribute electricity and natural gas to most of central and southern Illinois and to much of northern and eastern Missouri.

2023: Sierra Club report on Labadie Energy Center

In 2023, a Sierra Club report listed Ameren's Labadie Energy Center as one of the 17 deadliest coal plants in the US, urging the EPA to regulate harmful emissions contributing to regional haze. The report also highlighted that Labadie is the second-largest producer of greenhouse gases among the nation’s coal plants.