Minor civil divisions (MCDs) are the primary governmental or administrative divisions of a county or county equivalent in many states. MCDs represent many different kinds of legal entities with a wide variety of governmental and/or administrative functions. MCDs are variously designated as American Indian reservations, assessment districts, boroughs, charter townships, election districts, election precincts, gores, grants, locations, magisterial districts, parish governing authority districts, plantations, precincts, purchases, road districts, supervisor's districts, towns, and townships. In some states, all or some incorporated places are not located in any MCD (independent places) and thus serve as MCDs in their own right. In other states, incorporated places are part of the MCDs in which they are located (dependent places), or the pattern is mixed- some incorporated places are independent of MCDs and others are included within one or more MCDs. Independent cities, which are statistically equivalent to a county, also are treated as a separate MCD equivalent in states containing MCDs. In Maine and New York, there are American Indian reservations and off-reservation trust lands that serve as MCD equivalents; a separate MCD is created in each case where the American Indian area crosses a county boundary.
The U.S. Census Bureau recognizes MCDs in the following 28 states: Arkansas, Connecticut, Illinois, Indiana, Iowa, Kansas, Louisiana, Maine, Maryland, Massachusetts, Michigan, Minnesota, Mississippi, Missouri, Nebraska, New Hampshire, New Jersey, New York, North Carolina, North Dakota, Ohio, Pennsylvania, Rhode Island, South Dakota, Vermont, Virginia, West Virginia, and Wisconsin. The District of Columbia has no primary divisions, and the city of Washington is considered equivalent to an MCD for statistical purposes. Arlington County, VA, also has no MCDs and the entire county is designated as an MCD with the name Arlington.
The MCDs in 12 states (Connecticut, Maine, Massachusetts, Michigan, Minnesota, New Hampshire, New Jersey, New York, Pennsylvania, Rhode Island, Vermont, and Wisconsin) also serve as general-purpose local governments that generally can perform the same governmental functions as incorporated places. The U.S. Census Bureau presents data for these MCDs in all data products in which it provides data for places.
The cartographic boundary files are primarily designed for small scale, thematic mapping applications at a target scale range of 1:500,000 to 1:5,000,000.
Because of coordinate thinning:
1. Cartographic boundary files should not be used for geocoding;
2. Some offshore, redundant, zero population and housing land areas may be absent from the files;
3. Cartographic Boundary files are not necessarily vertically integrated with previous boundary file sets.