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 the county; for example, Central Hancock unorg. and East Hancock unorg. These measures make it easier for data users to refer to these areas on maps and in the Census Bureau’s data presentations.

The Census Bureau classifies a few other geographic entities as MCD equivalents. It treats the District of Columbia as an entity statistically equivalent to a State, and as a single county equivalent with the same name. The District of Columbia also is coextensive with the incorporated place of Washington city. The Census Bureau uses a single MCD, also called Washington, to represent the same geographic area recognized as the city, county equivalent, and State equivalent. Arlington County, Virginia, represents a similar situation, where no MCD exists within the county area. The Census Bureau recognizes a pseudo MCD to cover the entire county-level area and gives it the same name as the county.

In the TIGER data base, there exists water area within the Atlantic Ocean and Great Lakes that is not assigned to any land MCD. The Census Bureau assigns these waters to an MCD entity identified by a code of 000, and includes the measurement figures for them as part of the county total. No other data are published for these entities.

The purpose of CCDs is to provide a set of subcounty units that (1) have community orientation; (2) have visible, stable boundaries; (3) conform to groupings of census tracts or block numbering areas (BNAs); and (4) have a recognizable name.

Each CCD should be focused on one or more communities or places, and take in the additional surrounding territory that is served by these in some fashion. The definition of community takes into account factors such as production, marketing, consumption, and the integrating factor of local institutions. This criterion is an application of the functional integration principle that the Census Bureau uses to create some geographic statistical entities (for details, refer to ). County Subdivisions8-17