County Subdivision
A geographic subdivision of a county recognized by the Census Bureau, including townships, towns, election precincts, and minor civil divisions.
County subdivisions are the Census Bureau's term for the geographic entities between counties and Census tracts in the administrative hierarchy. The specific type of subdivision varies by state: New England uses towns, the Midwest uses townships, and the South and West often use Census county divisions (CCDs) — statistical units drawn by the Census Bureau where no local government subdivision exists.
There are roughly 36,000 county subdivisions nationwide. In states with strong township governments (Michigan, New Jersey, Pennsylvania), the subdivision is a functioning unit of local government. In other states, it serves only as a statistical reporting area.
County subdivision data can be useful in ZIP code analysis for identifying tax jurisdictions and local government service areas that do not align with city or ZIP code boundaries.