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 Chapter 4

States and counties are the major legally defined political and administrative units of the United States. As such, they serve as the primary geographic units for which the Bureau of the Census reports data. The Census Bureau provides statistics for these entities in every decennial census of population and housing, in every census of agriculture and governments, and in all the economic censuses. It tabulates data for States and counties in postcensal estimates and sometimes in its various intercensal sample surveys and projections as well. In certain circumstances, it classifies entities as the statistical equivalents of States or of counties for data presentation purposes.

Because States, counties, and statistically equivalent entities are an integral part of many Census Bureau data presentations, they occupy a prominent position in the hierarchy of the basic geographic entities (see in ). Therefore, a major responsibility of the Census Bureau is to maintain accurate maps and records of the boundaries and names of these entities, and to identify their populations and other data items correctly throughout the various phases of the census process. This chapter describes the framework of the States, counties, and statistically equivalent entities used by the Census Bureau, and explains their function as geographic units in the process of data collection, tabulation, and dissemination.

The United States comprises the 50 States and the District of Columbia. For data presentation purposes, the Census Bureau treats the District of Columbia as the statistical equivalent of a State. Depending upon Federal law and the scope of a particular census, sample survey, estimate, or projection, the Census Bureau may apply the same treatment to the territories under U.S. sovereignty or jurisdiction; for the 1990 decennial census, these included American Samoa, Guam, the Northern Mariana Islands, Palau, Puerto Rico, and the Virgin Islands of the United States. For several other entities under U.S. jurisdiction, the Census Bureau publishes only decennial census population counts and area measurements; for the 1990 census, these were the States, Counties, Equivalent Entities4-1