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 and names of local governments (counties, minor civil divisions, and incorporated places), and to ascertain whether changes have occurred in these entities. The Census Bureau obtains information about counties by sending questionnaires and maps to an official of each county (parish in Louisiana) in the United States, excluding Alaska, Connecticut, Hawaii, and Rhode Island; in these States, because of the unusual status of the counties (boroughs in Alaska), the Census Bureau works with the appropriate State authorities to obtain the required information. However, new counties (and boroughs in Alaska) are such a rare and major event that they usually come to the Census Bureau’s attention long before, and separate from, the annual BAS mailout. The Census Bureau obtains official confirmation and documentation of new counties, their boundaries, and their names from appropriate State officials.

Any changes in county boundaries may reflect changes in State boundaries as well. The proper location of State and county boundaries on Census Bureau maps is a vital element of the data collection and tabulation process. The BAS enables the Census Bureau to maintain, on a consistent basis, reasonably current records about changes in county boundaries that occur through resurveying, legal actions, or other transfers of territory that relocate county lines. In this way, the Census Bureau also accounts for changes in State lines as reported by the counties on either side of the State boundary.

The Census Bureau uses a system of numeric codes to identify every geographic entity in its hierarchy. These geographic codes are basic components of the geographic reference files that the Census Bureau develops and maintains to process the results of its censuses and sample surveys. The codes obviate the need to relate data to the geographic entities by name; that is, the Census Bureau’s processing operations associate data with the much shorter, fixed-length, unique numeric codes rather than the variable-length names of the geographic entities in its reference files. These files provide the basis for the tabulation and dissemination of the collected data in their proper geographic units. 4-14States, Counties, Equivalent Entities