- Puerto Rico—78 municipios
- The Virgin Islands of the United States—3 islands
The formation of States and counties has been an important theme in the political and social history of the United States as the Nation acquired new areas, settled them, and organized territorial, State, and local governments. The present State boundaries evolved as the Nation expanded westward; at the same time, counties developed and spread as units of local government and administration within the States and territories. There were more than 2,000 counties formed in the period from 1790 to 1900. The various censuses of the United States have recognized these governmental units since the earliest enumerations.
The system of individual States within a Federal union has its roots in the American colonial experience. By the time of the American Revolution, the identity and boundaries of the original 13 States had been evolving during 150 years of British colonization and settlement. Under British rule, the colonial legislatures gradually achieved various degrees of autonomy and self-government. The present Federal Union began in 1789 under the Constitution. The original 13 States joined the United States by their act of ratification. Article IV, Section 3, of the Constitution provides for the admission of additional States. Thereby, both the national and State governments share the power to admit additional States. In the future, as in the past, an area could achieve statehood only by an act of Congress that follows the broad guidelines of this Constitutional provision.
In the colonial period, census-taking was a familiar element of the American scene; the colonial authorities undertook 27 enumerations of the various colonies between 1624 and 1773. Article I, Section 2, of the Constitution calls for a population census as the basis for apportioning the seats in the Congress. The requirement for a census and, implicitly, the recognition of States in the geographic structure of the Census Bureau’s
States, Counties, Equivalent Entities4-3
