[2] In 1910, the Mattoon City Railway was reorganized as the Central Illinois Public Service Company.
The merger brought the company's holdings to seven generating stations, 15 ice plants, and two interurban railways.
[2] In November 1949, a winter ice storm hit central Illinois, bringing down both CIPS primary and high-voltage transmission lines.
[2] By the early 1990s, Central Illinois Public Service Company, an electric and natural gas utility, was reorganized as a subsidiary under its new holding company, CIPSCO Inc., which in turn continued to publicly trade on the stock exchange under the utility's old ticker symbol, CIP.
[3] In 1993, CIPSCO battled a 500-year flood in metropolitan St. Louis from the swollen Missouri and Mississippi Rivers.
[2] At the time of the merger, CIPSCO had assets of about US$210 million, but still carried nearly half of US$1 billion in long-term debt, which it had accumulated by the 1980s.
AmerenCIPS, along with subsidiaries AmerenIP and AmerenCILCO, have been criticized for not making proper preparations for the hikes in energy prices which were passed on to customers.