The more than 3,273 traditional electric utilities in the United States are responsible for ensuring an adequate and reliable source of electricity to all consumers in their service territories at a reasonable cost. Electric utilities include investor-owned, publicly-owned, cooperatives, and Federal utilities. Power marketers buy and sell electricity, but usually do not own or operate generation, transmission, or distribution facilities. Utilities are regulated by local, State, and Federal authorities, and in the case of many electric cooperatives, by their Board of Directors.