Table 4-4 lists the number of counties and equivalent entities in each State and the District of Columbia on January 1, 1990. Between the 1980 and 1990 decennial censuses, Arizona and New Mexico each established an additional county, and Alaska established two additional boroughs. One of the boroughs established in Alaska (Northwest Arctic) in effect replaced a census area (Kobuk), resulting in a net increase of two statistically equivalent entities. Nevada formed the new county of Bullfrog in 1987; however, its creation was nullified by the courts in 1988. The total number of counties and statistically equivalent entities at the time of the 1990 census was 3,141. In Alaska, two additional entities, Denali borough (established December 1990) and Yakutat borough (established 1992), have been formed since the 1990 census.
States and the statistically equivalent entities for which the Census Bureau tabulates data are legal entities, with boundaries prescribed by laws, treaties, and other governmental actions. Title 13, United States Code, in Chapter 5, “Censuses,” Subchapter II, sections 141(a) and (b), mandates the counting and tabulating of the population of the individual States and entities. Therefore, the Census Bureau uses the States, the District of Columbia, and the territories of the United States as a primary level of geography; it retains their identity throughout the data collection, tabulation, and dissemination phases of every census.
Much the same situation applies to the Nation’s counties and other statistically equivalent entities. All but a few of these entities are defined legally; that is, they are created by State law or some other administrative action. State constitutions or other laws generally specify counties (parishes in Louisiana, boroughs in Alaska, independent cities in four States) as the divisions of each State, and assign responsibilities to them for providing various aspects of local government. On this basis, it is logical for the Census Bureau to use these entities as the major geographic units in its data products. In addition, because counties and similar entities generally encompass the entire land area of each State and statistically equivalent
