Commonwealth Edison Company, also known as ComEd, is one of the largest electric utilities in the United States. It serves more than 3.5 million customers in northern Illinois. The company maintains over 90,000 miles of power lines and electric transmission and distribution systems. Commonwealth Edison Company has a staff of nearly 5,500 employees. It sponsors several schools, museums, performing arts centers, and civic, cultural and nonprofit organizations throughout Illinois. The company has received the City of Chicago s Environmental Excellence Award and the Solar Electric Power Association s Business Achievement Award. Commonwealth Edison Company is a unit of Exelon Corporation, which distributes electricity to approximately 5 million customers in Illinois.