Investor-owned utilities serve three out of every four utility customers in the United States, according to the U.S. Energy Information Administration's (EIA) survey data.

Investor-owned utilities (IOUs) are large electric distributors that are most common in heavily populated areas on the East and West coasts. In 2017, 168 IOUs served an average of 654,600 electric customers. Pacific Gas and Electric and Southern California Edison Company, both of which are located in California, are the two largest IOUs with 5.48 million customers and 5.07 million customers, respectively.

Publicly-owned utilities (POUs) include federal-, state-, and municipal-run utilities. The United States has 1,958 POUs which have an average of 12,100 electricity customers each. The largest POUs are the state-run Puerto Rico Electric Power Authority (PREPA), which has 1.47 million customers, and the Los Angeles Department of Water and Power, which is a municipal utility with 1.43 million customers.

Cooperatives are not-for-profit member-owned utilities. Co-ops are located in 47 states but are most common in the Midwest and Southeast.

The United States has 812 co-ops, which have an average of 24,500 electricity customers each. The largest cooperative is Pedernales Electric Co-op in Johnson City, Texas, with 333,809 customers, nearly 50 percent more customers than the second-largest co-op, Jackson Electric Member Corporation in Jefferson, Ga.

According to EIA, almost 3,000 electric distribution companies were operating in the United States in 2017. EIA groups utilities into three ownership types: investor-owned utilities, publicly run or managed utilities and cooperatives.

Investor-owned utilities make up a relatively small portion of utilities but are typically very large.

Source: EIA