Computers can be extremely useful in the delimitation process[1]. They can reduce the time required to draw redistricting plans and also aid in the evaluation of plans. They can produce detailed maps and statistics based on the demographic and political information in the redistricting database. And because computers allow redistricters to create plans more quickly, they enable redistricters to generate a larger number of redistricting plan alternatives for comparison and evaluation.
In the United States, about half the states used computers when congressional districts were redrawn after the 1980 census. In most of these states, computers were used as "super calculators" to summarise demographic and political data and to produce printouts of demographic information for the proposed districts.Today, all states use GIS systems.
Two important developments in the late 1980s contributed to a far greater use of computers for upcoming redistricting. These were (1) the development and the extensive use of powerful, affordable desktop computers and (2) the development of geographic information systems (GIS) software.
By 1990, every state in the United States used computers for redistricting, and almost every state used GIS software. The move towards computer-assisted redistricting was also aided by the availability of detailed demographic and geographic data in computer readable format from the U.S. Census Bureau.
Computer Software
Redistricters have several different options from which to choose with regard to software. A simple spreadsheet or database program can calculate the statistics that are commonly used in redistricting, such as total population, racial composition or overall population deviation from the electoral quota.
The resources necessary to employ computer technology for redistricting include:
- a computer (preferably desktop)
- spreadsheet or database software, or GIS software
- population and, if desired, political data available in electronic form (if only paper copies of the information are available, the data will have to be keypunched into the computer program)
- maps (either paper maps or digitised maps if GIS software is to be used)
A more sophisticated and more expensive option is GIS software.
Notes:
[1] This discussion draws heavily from an article written by Carlton Henry entitled "The Impact of New Technology and New Census Data on Redistricting in the 1990s." This article appeared in Redistricting in the 1990s: A Guide for Minority Groups, edited by William O'Hare and published by the Population Reference Bureau, Inc. in 1989.
