Geographic integrity

Geographic integrity is one of the neutral redistricting criteria that seeks to preserve the natural geographical boundaries such as counties, county subdivisions like MCDs, and places like cities. The general requirement for integrity is that a plan should seek to avoid unnecessary chops of a geographical unit. A more specific requirement for integrity is to mandate that certain geographical units like counties be preserved first, then other units should be preserved if a county must be split. This creates a hierarchy for integrity among the geographic units.

The county (or equivalent) is the most important unit for geographic integrity. If a state is divided into counties every resident is in a county, and county residency is recognized by the public. States use county structure to provide many services, especially election control and tabulation. The Census uses counties as the primary division of the states. The combination of universal coverage and election services make counties the natural geographic unit to preserve.

In states with recognized MCDs, it is easy to use them as the preserved unit in a hierarchy. The hierarchy can also extend larger than the county using metropolitan areas that are defined in terms of contiguous groups of one or more counties.

In many states places such as cities and villages pose a problem. Not all residents are in incorporated municipalities, they can span county and township lines, and are not always recognized as county subdivisions themselves. If municipal integrity is important then it requires balancing the municipal integrity with county integrity.

One way to accommodate places in a framework of counties and subdivisions is to recognize plans that are better at preserving place integrity. For example the plans below have five counties A-E and a city shown as a circle. Both plans have three chopped counties, but the plan at left also chops the city. The plan at right would be preferred since it preserves the city's integrity.