What is "census tract"

A census tract, census area, census district or meshblock is a geographic region defined for the purpose of taking a census. Usually 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, census tracts average about 4,000 inhabitants."