Commonwealth Edison
A regulated electric transmission and distribution utility serving Chicago and much of Northern Illinois.
Last updated October 16, 2026
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Overview
Commonwealth Edison, generally known as ComEd, is the principal electric delivery utility for Chicago and a large part of Northern Illinois. It is a subsidiary of Exelon Corporation and operates a regulated transmission and distribution network rather than functioning primarily as a competitive electricity-generation company. The utility serves more than 3.8 million customers across a territory extending approximately from Iroquois County in the south to the Wisconsin border in the north, and from the Illinois–Iowa region in the west toward Indiana in the east. Its customer base includes households, commercial properties, manufacturers, public institutions and other large users of electricity. ComEd traces its origins to the early development of commercial electric lighting in Chicago. The Isolated Lighting Company was established in 1881 to market small Edison generators and lighting equipment. It was succeeded in Chicago by the Western Edison Light Company, which installed an early incandescent lighting system in the home of investor John W. Doane in 1882. In 1887, municipal franchise holders created the Chicago Edison Company, which assumed Western Edison's local business. The company opened its first central generating station in 1888 and initially operated a direct-current network concentrated in the central city. Samuel Insull became president of Chicago Edison in 1892 and shaped the enterprise's long-term structure. He pursued consolidation of competing electric companies, promoted large generating stations and emphasized economies of scale, centralized management and extensive transmission infrastructure. By the middle of the 1890s, Chicago Edison had acquired enough competing operations and equipment rights to establish a dominant position in its service area. The company expanded its generating capacity through facilities including the Harrison Street and Fisk stations, helping electricity become a utility service delivered over a broad network rather than a collection of small, building-specific systems. Chicago Edison combined with Commonwealth Electric in 1907 to create Commonwealth Edison Company. The company subsequently absorbed Cosmopolitan Electric Company in 1913, strengthening its position as Chicago's primary electric provider. Its broader Northern Illinois presence also developed through related businesses, including Public Service Company of Northern Illinois and the 1967 acquisition of Rockford-based Central Illinois Electric and Gas Company. These activities extended service beyond the historic Chicago core and supported the region's transition toward widespread electrification. The structure of the American electric industry changed substantially during the 1990s. Illinois legislation adopted in 1997 introduced customer choice, reduced and froze certain electricity prices, and required utilities to participate in competitive procurement. In response, Commonwealth Edison separated much of its generation business from its delivery operations. Coal-fired generating stations were sold to Midwest Generation in 2000, while nuclear assets were transferred to Exelon Nuclear in 2003. The company thereby became more clearly focused on delivering electricity through its regulated wires, while generation and competitive supply were handled elsewhere within the broader corporate structure or by outside suppliers. In 1994, ComEd was reorganized under Unicom Corporation, and in 2000 Unicom merged with PECO Energy to form Exelon. Commonwealth Edison became one of Exelon's principal operating utilities. Today, ComEd's business centers on maintaining and modernizing distribution and transmission assets, connecting customers, managing outages, supporting electrification and complying with Illinois utility regulation. Its network includes transmission facilities operating at several high-voltage levels, including 765 kV, 345 kV, 138 kV and 69 kV, as well as lower-voltage sub-transmission infrastructure. The company…
History
Commonwealth Edison developed from Chicago's earliest commercial electric-lighting ventures. In 1881, George H. Bliss established the Isolated Lighting Company as a subsidiary associated with Thomas Edison's businesses. The enterprise marketed small generators and lighting installations intended for individual buildings or small clusters of nearby premises. The Western Edison Light Company succeeded it in Chicago and pursued a central-station model. One early installation illuminated the Chicago home of company investor John W. Doane in November 1882. In 1887, John M. Clark, Robert Todd Lincoln and John B. Drake secured a city franchise for electricity distribution in a central Chicago area. They formed the Chicago Edison Company, which took over Western Edison's local operations in July of that year. Its first central station opened on West Adams Street in August 1888. The station used Edison's direct-current technology and initially served a compact downtown territory. Increasing demand soon made the facility inadequate. Samuel Insull became president of Chicago Edison in May 1892. He viewed the fragmented Chicago electricity market as inefficient and worked toward a regulated-monopoly model in which a utility would receive exclusive rights within a defined territory while remaining subject to public oversight of service and prices. Before formal state utility regulation became established, Insull consolidated competing local companies and acquired associated equipment rights. By 1895, Chicago Edison had achieved a dominant position in its territory. Insull also expanded generating capacity. The Harrison Street station opened in 1894 with an ambitious initial capacity of 6,400 kilowatts, then one of the largest central stations in the United States. Its output was expanded as demand grew. The Fisk Generating Station later introduced large steam turbines, reflecting the industry's movement toward centralized generation and economies of scale. Insull also supported the creation of Public Service Company of Northern Illinois, which helped extend electric service into areas outside Chicago. Chicago Edison merged with Commonwealth Electric in 1907, forming Commonwealth Edison Company. In 1913, the company absorbed Cosmopolitan Electric Company, consolidating its position as Chicago's main electric provider. Related expansion continued through acquisitions and affiliated companies. In 1967, Commonwealth Edison acquired Central Illinois Electric and Gas Company, based in Rockford, adding service territories around Rockford and Lincoln, Illinois. The company was part of Samuel Insull's wider utility structure until the collapse of Middle West Utilities during the Great Depression. Over the following decades, Commonwealth Edison operated as a major vertically integrated electric utility, combining generation, transmission and distribution. Its later history was shaped by the national movement toward competition and restructuring in electricity markets. In 1994, Commonwealth Edison reorganized as a subsidiary of Unicom Corporation. Illinois's 1997 Electric Service Customer Choice and Rate Relief Law opened electricity supply to competitive alternatives, reduced residential rates and established a period of rate controls. The regulatory changes encouraged Commonwealth Edison to divest generation assets and focus more clearly on delivery infrastructure. Coal-fired stations were sold to Midwest Generation in 2000, while nuclear generating assets were transferred to Exelon Nuclear in 2003. Unicom merged with PECO Energy in 2000 to create Exelon Corporation. Commonwealth Edison became a principal Exelon operating company, retaining its ComEd identity and responsibility for regulated electric delivery in Northern Illinois. The separation of generation from delivery did not eliminate political or economic controversy. The end of the Illinois rate freeze produced a contentious 2007 rate case involving proposed delivery increases and competitive procurement of electricity. The dispute contributed to the creation of the Illinois Power Agency, which assumed a role in arranging electricity procurement for Illinois utilities. ComEd's recent corporate history also includes a major federal corruption investigation. In 2020, the company agreed to pay $200 million in connection with allegations that it used jobs, contracts and other benefits to influence political decision-making. Former executives and associates were later prosecuted, and four defendants were convicted in 2023. Despite these controversies, ComEd continues to operate as an active regulated utility, maintaining a large Northern Illinois distribution network, high-voltage transmission interconnections, customer meters and outage-response operations.
- 2023
Four defendants convicted in ComEd bribery case
[1]A former ComEd chief executive, a former lobbyist and two associates were convicted on bribery-related charges.
- 2020
Federal corruption settlement
[1]ComEd agreed to pay $200 million in connection with a federal investigation into alleged political influence and improper contracts.
- 2007
New rate plan takes effect
[1]A new ComEd rate plan began after a contentious debate over delivery charges, procurement and a proposed extension of the rate freeze.
- 2003
Nuclear generation transferred
[1]Commonwealth Edison transferred its nuclear generating stations to Exelon Nuclear as its delivery-focused role became more pronounced.
- 2000
Exelon formed and coal generation divested
[1]Unicom merged with PECO Energy to form Exelon, while Commonwealth Edison sold its coal-fired generating stations to Midwest Generation.
- 1997
Illinois customer-choice legislation enacted
[1]Illinois adopted legislation opening electricity supply to competition and changing utility pricing and procurement requirements.
- 1994
Reorganized under Unicom
[1]Commonwealth Edison became the leading subsidiary of Unicom Corporation.
- 1967
Central Illinois Electric and Gas acquired
[1]Commonwealth Edison acquired the Rockford-based utility, adding service territories around Rockford and Lincoln.
- 1913
Cosmopolitan Electric absorbed
[1]The company acquired Cosmopolitan Electric Company, reinforcing its dominant position in Chicago.
- 1907
Commonwealth Edison Company created
[1]Chicago Edison merged with Commonwealth Electric to form Commonwealth Edison Company.
Products and positioning
Regulated electric transmission and distribution utility
Utility service
Residential electricity delivery
ComEd delivers electricity to households throughout Chicago and much of Northern Illinois through its regulated distribution network. The service includes connection to the local grid, metering, billing-related delivery functions, maintenance of distribution equipment and restoration of service following outages. Customers may obtain electricity supply through competitive arrangements, but ComEd remains responsible for the regulated delivery infrastructure in its territory.
Utility service
Commercial and industrial electricity delivery
ComEd serves businesses, manufacturers, public agencies and other non-residential customers. Its offering includes higher-capacity connections, distribution-system operation, metering and service support for customers with substantially larger or more complex electricity loads than residential users.
Grid infrastructure
Electric transmission
The company operates high-voltage transmission assets and interconnections that move electricity across Northern Illinois and connect its system with neighboring utilities. Reported operating voltages include 765 kV, 345 kV, 138 kV and 69 kV, supported by lower-voltage sub-transmission facilities.
Utility support service
Electric metering
ComEd installs, maintains and reads electric meters used to measure customer consumption and support billing and grid operations. Reference material identifies Aclara as a meter manufacturer used by the company.
Controversies
2023
ComEd Four convictions
Former ComEd chief executive Anne Pramaggiore, former lobbyist Mike McClain, retired executive John Hooker and former consultant Jay Doherty were convicted on bribery conspiracy, bribery and falsification-related charges. Prosecutors alleged that the group sought to influence former Illinois House Speaker Michael Madigan through jobs, contracts and other benefits.
2021
Citizens Utility Board sues ComEd over alleged bribery scheme
The Citizens Utility Board filed a federal lawsuit accusing Commonwealth Edison of unjust enrichment and betraying customers through an alleged bribery scheme to influence legislation. ComEd had admitted facts of the bribery scheme in a deferred prosecution agreement; a spokesperson said that admission did not mean consumers were harmed by the legislation.
2020
Federal political-influence and contract investigation
ComEd agreed to pay $200 million after a federal investigation into alleged illegal lobbying, political graft and favorable contracts involving political allies. The matter concerned efforts to influence Illinois political decision-making while the company pursued favorable treatment for its regulated utility business.
Marketing campaigns
- 2007Consumers Organized for Reliable Electricity advocacy campaign
Illinois
ComEd supported Consumers Organized for Reliable Electricity, an organization that opposed extending the Illinois electricity-rate freeze. Critics characterized the campaign as an astroturfing effort because corporate backing was not initially prominent in its public presentation. The Illinois Commerce Commission dismissed a petition seeking mandatory disclosure in the advertisements, although the organization agreed to make ComEd's support more explicit.
Outcome. The Illinois Commerce Commission dismissed a petition seeking mandatory disclosure in the advertisements, although the organization agreed to make ComEd's support more explicit.
Brand decisions
2007
Implementation of post-freeze rate planPrice changeBackground
The end of Illinois rate controls coincided with the expiration of favorable power-purchase arrangements and debate over how customers should pay for electricity delivery and supply.
Action taken
ComEd implemented a plan that raised average delivery rates by approximately 22 percent and used competitive procurement for electricity supply. The typical residential bill was expected to rise by about 33 percent.
Aftermath
Public opposition contributed to scrutiny of the procurement process and helped prompt creation of the Illinois Power Agency.
Estimated typical residential electric-bill increase. approximately 33% increase (Effective January 2, 2007)
2003
Transfer of nuclear generating assetsStrategyBackground
The company's generation and delivery businesses were being separated as Illinois moved toward competitive electricity supply.
Action taken
ComEd transferred its nuclear generating stations to Exelon Nuclear.
Aftermath
Generation remained within the wider Exelon group, while ComEd operated primarily as a regulated delivery company.
2000
Formation of Exelon through Unicom–PECO mergerM&ABackground
Unicom Corporation, whose leading subsidiary was Commonwealth Edison, combined with Philadelphia-based PECO Energy.
Action taken
The merger created Exelon Corporation and placed ComEd within a larger multi-utility holding company.
Aftermath
ComEd continued operating as Exelon's principal Northern Illinois electric delivery utility.
2000
Sale of coal-fired generating stationsStrategyBackground
Illinois electricity-market restructuring encouraged utilities to distinguish competitive generation from regulated delivery.
Action taken
ComEd sold its coal-fired generating stations to Midwest Generation.
Aftermath
The transaction reinforced ComEd's focus on electricity transmission and distribution rather than ownership of generation assets.
1997
Shift toward a competitive electricity marketStrategyBackground
Illinois legislation introduced customer choice, reduced certain residential rates and required utilities to obtain electricity through competitive processes after the rate-control period.
Action taken
ComEd adjusted its business structure and began separating generation from regulated delivery operations.
Aftermath
The company later divested coal-fired and nuclear generating assets, leaving transmission and distribution as the core of its operating identity.
Recent events
Reported
Citizens Utility Board sues ComEd over alleged bribery scheme[3]
The Citizens Utility Board filed a federal lawsuit accusing Commonwealth Edison of unjust enrichment and betraying customers through an alleged bribery scheme to influence legislation. ComEd had admitted facts of the bribery scheme in a deferred prosecution agreement; a spokesperson said that admission did not mean consumers were harmed by the legislation.
Sources3 sources
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