first several years, and was expanded to 16,200 kilowatts by 1903, the year Fisk Generating Station put large steam turbines into service. In 1907, Chicago Edison combined with Commonwealth Electric to form Commonwealth Edison Company. Six years later, it absorbed the independent Cosmopolitan Electric Company, and with that purchase effectively became the sole electric provider in Chicago. Insull also founded Public Service Company of Northern Illinois, which developed rural electrification in northern Illinois outside Chicago. Public Service and ComEd, along with many other companies, were subsidiaries of Insull's Middle West Utilities Company until Middle West's collapse during the Great Depression. According to at least one source Insull was also the earliest to develop transmission companies, in the 1920s, a concept that was undermined by the development of Public Utility Commissions, in general, and the Public Utilities Company Holding Act of 1935, in particular. Necessary regulation in that form has been overcome by recent deregulatory measures. In 1994, ComEd reorganized as a holding company, Unicom Corporation, with ComEd as its leading subsidiary. In 2000, UniCom merged with Philadelphia-based electric company PECO Energy to form Exelon. Deregulation and Divestiture By 1996, prevailing opinion on the utilities in the United States had changed. Rather than granting one company the exclusive right to generate, transmit and distribute electricity in a specific geographic area, and fixing the rates for that service as one package, it was commonly held that consumers would benefit from opening as much service as possible to competition on an open market. At the federal level, the Federal Energy Regulatory Commission had issued Order 888, opening access to the national transmission grids. Subsequent orders established an open energy marketplace and set rules for participation in it. However, it was left to the individual states to determine the best way to give their electricity customers access to the grid and the benefits of an open market. For Illinois, the General Assembly passed the Electric Service Customer Choice and Rate Relief Law of 1997. The law ordered most Illinois electric utilities (including Commonwealth Edison) to provide their customers with the option of buying electricity from other suppliers. It also reduced base residential electric prices by 15%, with a further 5% decrease effective in 2001, and froze the reduced rates for ten years. Finally, it obligated the utilities, at the end of that ten-year period, to obtain their electricity through a competitive process. These rules