Census tracts

A census tract, census area, census district or meshblock is a geographic region defined for the purpose of taking a census. Sometimes these coincide with the limits of cities, towns or other administrative areas and several tracts commonly exist within a county. In unincorporated areas of the United States these are often arbitrary, except for coinciding with political lines.

Census tracts represent the smallest territorial unit for which population data are available in many countries. In the United States, census tracts are subdivided into block groups and census blocks. In Canada they are divided into dissemination areas. In the U.S., census tracts are "designed to be relatively homogeneous units with respect to population characteristics, economic status, and living conditions" and "average about 4,000 inhabitants".

In New Zealand census tracts are known as meshblocks, or mesh blocks, and are defined by Statistics New Zealand as being "the smallest geographic unit for which statistical data is collected and processed by Statistics New Zealand". It is a defined area, varying in size from part of a city block to large areas of rural land. Each of these borders another to form a network covering the whole country including inlets and coasts, and extending out to the 200 mile economic zone. Meshblocks are added together to "build up" larger geographic areas such as area units and urban areas. They are also used to draw up and define New Zealand electorates and local authority boundaries.

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.

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