Census tracts are small, relatively permanent statistical subdivisions of a county.
Census tracts are delineated for all metropolitan areas and other densely populated counties by local census statistical area committees following Census Bureau guidelines. The major difference between census tracts and BNAs is that BNAs typically contain fewer people. Census tracts usually have between 2,500 and 8,000 people, and, when first delineated, are designed to be homogeneous with respect to population characteristics, economic status, and living conditions. The spatial size of census tracts varies widely depending on the density of settlement.