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 operates as a holding company for various power and energy providers. Ameren serves 2.4 million electric and 900,000 natural gas customers across a significant area encompassing central and eastern Missouri, and most of southern Illinois.

1921: CILCO Pays Dividend

Since 1921, Central Illinois Light Company (CILCO) had been paying a dividend.

1929: Bagnell Dam Completion

In 1929, the Bagnell Dam was completed on the Osage River, generating approximately 175 megawatts of hydroelectricity for Missouri's Union Electric Company and creating 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, located 150 miles north of St. Louis, to augment their generating sources, and later bought the dam, providing 134 megawatts of hydroelectricity.

1947: Illinois Power Paying Dividends

Since 1947, Illinois Power Company has been paying dividends.

1952: CIPS Joins Midwest Power Pool

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

1952: Illinois Power Joins Power Pool

In 1952, Illinois Power Company was the third partner of the Midwest Power Pool system.

1963: Taum Sauk Plant Construction

In 1963, Union Electric completed construction of the Taum Sauk Plant, a 350-megawatt pumped storage 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 in Callaway County, Missouri, providing 1,143 megawatts of power.

1991: Illinois Power Reorganized

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

1994: NGC Integrated Natural Gas Services Company

NGC had been an integrated natural gas services company around since 1994.

1995: Merger Approved

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

1996: CILCO Asset Growth

By 1996, Central Illinois Light Company (CILCO) had grown to over US$150 million in assets.

1996: Illinova Grown to S&P Midcap 400 Stock

By 1996, Illinova had grown to an S&P Midcap 400 stock, with over US$415 million in assets, and had brought the IP utility's debt down to US$1.8 billion by then.

December 31, 1997: Ameren Corporation Creation

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. Created

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

1999: Medicare Study on Coal Plant Air Pollution

A study published in Science used Medicare records to estimate the number of deaths tied to air pollution from coal plants, estimating that from 1999 to 2020, about 4,000 deaths were linked to “fine particulate matter” from Labadie.

February 1, 2000: Illinova and Dynegy Merger

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

2000: AmerenEnergy Resources Formed

In 2000, Ameren formed AmerenEnergy Resources as a holding company with two 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 to realize significant long-term savings.

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 CILCORP, Inc. and its subsidiary, Central Illinois Light Company (CILCO), from AES Corporation, after which CILCO began operating as AmerenCILCO.

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

In December 2004, Patrick T. Stokes, president and chief executive officer 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., after which the subsidiary began operating as AmerenIP.

December 14, 2005: Taum Sauk Plant Failure

On December 14, 2005, the Taum Sauk pumped storage plant, owned by Ameren Missouri, failed, causing damage and leading to fines and lawsuits.

2007: Modifications at Rush Island Plant

From 2007 through 2010, Ameren undertook major modifications at the Rush Island Plant.

2009: Wind Power Agreement

In 2009, AmerenUE signed an agreement to purchase 102 megawatts (MW) of wind power from Horizon Wind Energy's Pioneer Prairie Wind Farm in Iowa.

2009: Ameren UE Tower Construction

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

April 21, 2010: Taum Sauk Hydroelectric Plant Resumes Operation

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

October 1, 2010: Ameren Illinois Company 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: Add Renewable Capacity

By 2010, AmerenUE fulfilled commitment to add 100 megawatts of renewable capacity to serve its Missouri customers.

2010: Business as AmerenUE

Following the merger, Union Electric began doing business as AmerenUE, now known as Ameren Missouri. Today, with nine power plants Ameren Missouri serves 1.2 million power customers and 110,000 gas customers, primarily in Missouri, where more than half of its customers reside in the St. Louis metropolitan area. It also served Iowa as well through the mid-1990s, and served adjoining parts of Illinois until 2010.

2010: Modifications at Rush Island Plant

From 2007 through 2010, Ameren undertook major modifications at the Rush Island Plant.

2010: EPA Notice of Clean Air Act Violations

In at least 2010 and 2011, Labadie received notice of Clean Air Act violations from the EPA, cited for “major modifications that caused a significant net emissions increase” without obtaining proper permits.

2011: EPA Lawsuit Filed

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

June 2014: Contaminated Soil Removal

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

September 2014: Soil Removal Completion

In September 2014, Ameren expected to complete contaminated soil removal from the former coal gasification plant in Columbia, Missouri.

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 Failed

In 2016, Ameren attempted to launch a pilot program to install electric vehicle charging stations but was denied by state utility regulators.

2016: Ranked Among Best Energy Companies

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

January 2017: Liability Finding and Remedy Order

In January 2017, a District Court found Ameren liable for violating the Clean Air Act and ordered the company to equip its Rush Island plant with scrubbers.

January 23, 2017: Ameren Violated Clean Air Act

On January 23, 2017, the District Court found that Ameren violated the Clean Air Act.

2017: Shareholder Profile

As of 2017, Ameren shares are mainly held by institutional investors.

2018: "Charge Ahead" Program Launched

In early 2018, Ameren launched the "Charge Ahead" program to incentivize the installation of charging stations and the adoption of commercial electric vehicles.

2019: City Considering Purchase

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

2021: Electricity Distribution

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 identified Ameren's Labadie Energy Center as one of the 17 deadliest coal plants in the U.S., urging the EPA to regulate harmful emissions that contribute to regional haze affecting nearby communities.