Governmental units within each state comprise counties, municipalities, and such special districts as those for water, sanitation, highways, parks. and recreation. There are more than 3,000 counties in the United States; more than 19,000 municipalities, including cities, villages, towns, and boroughs; nearly 15,000 school districts; and at least 31,000 special districts. Additional townships, authorities, commissions, and boards make up the rest of the nearly 85,000 local governmental units.
The 50 states are autonomous within their own spheres of government, and their autonomy is defined in broad terms by the 10th Amendment to the US Constitution, which reserves to the states such powers as are not granted to the federal government and not denied to the states. The states may not, among other restrictions, issue paper money, conduct foreign relations, impair the obligations of contracts, or establish a government that is not republican in form. Subsequent amendments to the Constitution and many Supreme Court decisions added to the restrictions placed on the states. The 13th Amendment prohibited the states from legalizing the ownership of one person by another (slavery); the 14th Amendment deprived the states of their power to determine qualifications for citizenship; the 15th Amendment prohibited the states from denying the right to vote because of race, color, or previous condition of servitude; and the 19th, from denying the vote to women.
Since the Civil War, the functions of the state have expanded. Local business—that is, business not involved in foreign or interstate commerce—is regulated by the state. The states create subordinate governmental bodies such as counties, cities, towns, villages, and boroughs, whose charters they either issue or, where home rule is permitted, approve. States regulate employment of children and women in industry, and enact safety laws to prevent industrial accidents. Unemployment insurance is a state function, as are education, public health, highway construction and safety, operation of a state highway patrol, and various kinds of personal relief. The state and local governments still are primarily responsible for providing public assistance, despite the large part the federal government plays in financing welfare.
Each state is headed by an elected governor. State legislatures are bicameral except Nebraska's, which has been unicameral since 1934. Generally, the upper house is called the senate, and the lower house the house of representatives or the assembly. Bills must be passed by both houses, and the governor has a suspensive veto, which usually may be overridden by a two-thirds vote.
The number, population, and geographic extent of the more than 3,000 counties in the United States—including the analogous units called boroughs in Alaska and parishes in Louisiana—show no uniformity from state to state. The county is the most conspicuous unit of rural local government and has a variety of powers, including location and repair of highways, county poor relief, determination of voting precincts and of polling places, and organization of school and road districts. City governments, usually headed by a mayor or city manager, have the power to levy taxes; to borrow; to pass, amend, and repeal local ordinances; and to grant franchises for public service corporations. Township government through an annual town meeting is an important New England tradition.
From the 1960s into the 21st century, a number of large cities began to suffer severe fiscal crises brought on by a combination of factors. Loss of tax revenues stemmed from the migration of middle-class residents to the suburbs and the flight of many small and large firms seeking to avoid the usually higher costs of doing business in urban areas. Low-income groups, many of them unskilled blacks and Hispanic migrants, came to constitute large segments of city populations, placing added burdens on locally funded welfare, medical, housing, and other services without providing the commensurate tax base for additional revenues.