In the American Public Land Survey System, a township refers to a unit of land, that is nominally six (U.S. Survey) miles (~9.656 km) on a side. Each 36 square mile (~93.240 km²) township is divided into 36 one-square mile (~2.590 km²) sections, that can be further subdivided for sale. The townships are referenced by a numbering system that locates the township in relation to a meridian (north-south) and base line (east-west).

Survey townships (sometimes referred to as Congressional townships) are distinct from civil townships. A survey township is used to establish boundaries for land ownership. A civil township is a form of local government. In states that use both forms, civil townships generally use the boundaries established by survey townships.