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 from legal actions, treaties, statutes, ordinances, resolutions, court decisions, and the like. Local officials and others require data for governmental entities to fulfill a variety of needs. They require the boundaries of legal and administrative entities to manage a wide variety of programs and to conduct elections. The Census Bureau generally accepts, according to documentation by the appropriate authorities, the boundaries of these entities as they exist. Although the Census Bureau’s data tabulations for legal and administrative entities are sufficient to satisfy the needs of many data users, information for these jurisdictions alone does not meet all data needs. Therefore, the Census Bureau also presents data for a second geographic category, statistical entities.

Statistical geographic entities usually evolve from practice, custom, usage, or need, and generally the Census Bureau develops the criteria and guidelines for their identification and delineation. In contrast to the legal and administrative entities, whose existence and boundaries are officially prescribed, statistical entities are appropriate in situations where the geographic coverage of the legal areas is incomplete, inadequate, or inconsistent over time, or is nonexistent. The Census Bureau develops statistical units in response to the programmatic or analytical needs of data users. In doing so, the Census Bureau, often in cooperation with State, local, and tribal officials, endeavors to establish a standard set of statistical entities whose size, composition, and boundaries meet the needs of its data presentations. The Census Bureau recognizes statistical entities at all levels in its decennial census geographic hierarchy (see and ).

This chapter summarizes some of the more important considerations that enter into the Census Bureau’s choice and use of legal/administrative and statistical geographic entities. To provide the data tabulations needed by a majority of users, the Census Bureau intermingles the legal/administrative and statistical entities within a common framework, the geographic hierarchy. The basic hierarchy has several levels (States, counties, and county subdivisions), with each comprising a level. American Indian and Alaska Native areas, metropolitan areas (MAs), urbanized areas (UAs), places, and other entities are interspersed throughout the framework. The diagrams 2-2Geographic Overview