Changes

Created by the year-end 1997 merger of Union Electric Company and CIPSCO, parent of Central Illinois Public Service Company, the company grew in 2003 with the acquisition of CILCORP, the parent of Central Illinois Light Company and again in 2004 with the acquisition of Illinois Power Company.At the end of 2009 it was announced that Ameren Energy Resources had spent $1 billion for the installation of [[scrubbers]] at two of its facilities, including the Duck Creek Station and the Coffeen Plant. The scrubbers reduce nitrogen oxide and sulfur dioxide emissions.<ref>[http://www.tradingmarkets.com/news/stock-alert/aee_aer-invests-1-billion-in-environmental-upgrades-in-illinois-690319.html AER invests $1 billion in environmental upgrades in Illinois,] TradingMarkets.com, accessed January 2010.</ref>