Minor civil division

A minor civil division (MCD) is a term used by the United States Census Bureau for primary governmental and/or administrative divisions of a county or county-equivalent, typically a municipal government such as a city, town, or civil township. MCDs are used for statistical purposes by the Census Bureau, and do not necessarily represent the primary form of local government. They range from non-governing geographical survey areas to municipalities with weak or strong powers of self-government. Some states with large unincorporated areas give substantial powers to counties; others have smaller or larger incorporated entities with governmental powers that are smaller than the MCD level chosen by the Census.

As of 2010, MCDs exist in 29 states, the District of Columbia, and Puerto Rico. In all other states where state-defined entities are not used for census purposes (mostly in the South and the West), the Census Bureau designates Census County Divisions (CCDs). For several decennial censuses prior to the 2010 census, 28 states used MCDs, but in 2008, Tennessee changed from CCDs to MCDs, bringing the total number of MCD states to 29.^[1]

In states that use MCDs, when any land or water is not covered by a state-defined MCD, the Census Bureau creates additional entities as unorganized territories, that it treats as equivalent to MCDs for statistical purposes. Because MCDs are used to divide up counties, when a MCD-level municipality or unallocated territory or water spans county boundaries, that entity's boundaries are used to create multiple MCDs, one for each county. For water areas unallocated to any MCD, the Census Bureau assigns a default FIPS county subdivision code of 00000 and an ANSI code of eight zeroes.^[1] This typically happens when state and county boundaries extend into the ocean or Great Lakes, but MCDs are not defined by the state for the unoccupied water. (For the ocean boundary of state vs. federal responsibility, see Tidelands.)