Delimitation, or redistricting, requires the collection of several different types of information. The two essential pieces of information are population data and maps. The population data, which may be in the form of census enumeration data or voter registration data, provide the only means of creating districts that are relatively equal in population. The population data must be associated with a specific geographic area and must be as accurate and up-to-date as possible. Maps are needed to ensure that only contiguous geographic population units are assigned to districts.
A third piece of information that may or may not be utilised for redistricting is political data. Political data usually refers to election results --tabulations of votes for candidates and ballot measures from previous elections by voting area. Including political data in the redistricting database allows line drawers to produce a political profile of proposed districts and to predict, to some degree, the partisan implications of a redistricting plan.
Election results can easily be entered into the redistricting database if they are reported for the same geographic unit as the population data. This will likely be the case when the population units for redistricting are based on voter registration data. If, however, the population units are based on a census enumeration, the geographic units for population and political data may not be the same. In that case, census geography and election geography may have to be matched in some manner to create geographic units that can be associated with both population and political data.
In the United States, for example, electoral districts are usually created using census geography (census blocks or tracts), but election results are reported at the voting area (election precinct) level. These two units of geography--census blocks and election precincts--are not equivalent. States that wish to use political data in conjunction with population data must develop some method of matching political data with the corresponding units of census geography (see also GIS - Geographical Information Systems).
use of population in delimitation
I look forward to a criteria which combines population and geographical spread as an ultimate way to spar development in the sparsely populated but geographically expansive areas. Any proposals pleas?