Census tracts (CTs) are small, relatively stable geographic areas that usually have a population of less than 10,000, based on data from the previous Census of Population Program. They are located in census metropolitan areas and in census agglomerations that had a core population of 50,000 or more in the previous census.

A committee of local specialists (for example, planners, health and social workers, and educators) initially delineates census tracts in conjunction with Statistics Canada. Once a census metropolitan area (CMA) or census agglomeration (CA) has been subdivided into census tracts, the census tracts are maintained even if the core population subsequently declines below 50,000.

Changes to census tract boundaries are discouraged to ensure data comparability between censuses. Boundary revisions rarely occur, and only when essential. Road construction, railroad abandonment, community redevelopment, neighborhood growth and municipal annexations may contribute to changes in boundaries. A census tract may be split into two or more new census tracts (usually when its population exceeds 10,000). CT splits are usually done in a way that allows users to re-aggregate the splits to the original census tract for historical comparison.