<P> British census tracts were first developed in the city of Oxford . The Inter-University Census Tract Committee was formed in 1955 and Oxford was divided into 48 tracts with an average population of 2,645 each . The Registrar General, however, opted for enumeration districts containing less than 1,000 people on average, rather than adopting census tracts . While tracts composed of enumeration districts were later developed, these were not extensively used . Census tracts have, however, been constructed and used by British demographers . The Office for National Statistics now uses enumeration districts only for the collection of data, with output areas used as the base unit in census releases . </P> <P> The concept of the census tract was first developed in the United States . In 1906, Dr. Walter Laidlaw originated the concept of permanent, small geographic areas as a framework for studying change from one decennial census to another in neighborhoods within New York City . For the 1910 Census, eight cities--New York, Baltimore, Boston, Chicago, Cleveland, Philadelphia, Pittsburgh, and St. Louis--delineated census tracts (then termed' ' districts' ') for the first time . No additional jurisdictions delineated census tracts until just prior to the 1930 Census, when an additional ten cities chose to do so . The increased interest in census tracts for the 1930 Census is attributed to the promotional efforts of Howard Whipple Green, who was a statistician in Cleveland, Ohio, and later the chairman of the American Statistical Association's Committee on Census Enumeration Areas . For more than 25 years, Green strongly encouraged local citizens, via committees, to establish census tracts and other census statistical geographic areas . The committees created by local citizens were known as Census Tract Committees, later called Census Statistical Areas Committees . </P> <P> After 1930, the Census Bureau saw the need to standardize the delineation, review, and updating of census tracts and published the first set of census tract criteria in 1934 . The goal of the criteria has remained unchanged; that is, to assure comparability and data reliability through the standardization of the population thresholds for census tracts, as well as requiring that their boundaries follow specific types of geographic features that do not change frequently . The Census Bureau began publishing census tract data as part of its standard tabulations beginning with the 1940 Census . Prior to that time, census tract data were published as special tabulations . </P> <P> For the 1940 Census, the Census Bureau began publishing census block data for all cities with 50,000 or more people . Census block numbers were assigned, where possible, by census tract, but for those cities that had not yet delineated census tracts,' ' block areas' ' (called' ' block numbering areas' ' (BNAs) in later censuses) were created to assign census block numbers . Starting with the 1960 Census, the Census Bureau assumed a greater role in promoting and coordinating the delineation, review, and update of census tracts . For the 1980 Census, criteria for BNAs were changed to make them more comparable in size and shape to census tracts . For the 1990 Census, all counties contained either census tracts or BNAs . </P>

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