10. Modesto, Calif.
Employment: 184,677
Union Members: 39,633
Membership Rate: 21.5 percent
Local and county government, which tend to have high unionization rates, are two major employers in the city of Modesto, according to the city's chamber of commerce. In 2010, Stanislaus County employed nearly 4,800, and the city itself employed an additional 1,400 workers. Hirsch and Macpherson estimate that 31 percent of all U.S. public administration employees are union members.
