Census tract

A census tract is a small subdivision of a county or equivalent area, drawn by a national statistics agency, the U.S. Census Bureau in the American case, to contain a relatively homogeneous population, typically a few thousand people, and to stay stable across censuses so trends can be tracked over time in the same geographic unit.

Tracts are the standard building block for publishing detailed demographic, income, and housing statistics below the city or county level, including figures from the decennial census and the American Community Survey; they are further subdivided into block groups and individual census blocks for even finer geography. Analysts join tract-level data to other datasets using a tract's GEOID or its boundary file, often within a geographic information system, to map or model local conditions and visualize them on a choropleth map.

Tracts are the geography most local social, economic, and public-health indicators are published at, including poverty rates and the gini coefficient, which makes them the default unit for local equity analysis and resource targeting, and a common input to small area estimation models. The main pitfall is that tract boundaries are drawn for statistical convenience, not to reflect neighborhood identity or the service areas agencies actually use, so tract-level results do not always line up with how residents or local government define a community.