largest us utility company
The 10 biggest U.S. electric utilities visualized. Duke Energy's merger with Progress Energy, completed in July 2012, created the largest electric utility in the United States. In fact, two of the three largest U.S. utilities are the result of recent mergers. Exelon, third on the list of the 10 biggest U.S. utilities, merged with Constellation Energy in March 2012. Duke will now service 7 million retail customers across six states.