Mechanics of Redistricting

Imagine a large table somewhere in a back room  of the State House. On it is unrolled a huge map, surrounded by lawmakers, each standing ready to mark their territory.  Of course, that’s not how it happens with modern redistricting. These days, it’s more point-and-click than magic markers and sharp elbows.

The mechanics of redistricting involves sophisticated mapping software that allows easy point-and-click district construction.  Vendors with names like Caliper and Esri offer dedicated redistricting programs. Open-source (free) software like QGis makes mapping readily available. As the maps are drawn, district statistics are displayed, changing dynamically as the lines move.  

Currently, some redistricting software providers sell versions that can be used online, including by citizen map drawers.  As artificial Intelligence continues to develop, redistricting will become more automated and rules-driven.

The core Census data file for redistricting includes both total population and voting age population for each layer, including census blocks, precincts, cities and towns, and counties.  Mappers may also easily add other data from the Census, IPums, SC Election Commission and data vendors, allowing narrow targeting.

Historically, the Census data has provided detailed racial and ethnic breakouts, but has not recently included citizenship. That may change in 2020.  The measure of one person, one vote in South Carolina comes down to how many people are found and willing to be counted in the Census.  That number will be used for all redistricting until the next Census, in 2030.

John C. Ruoff, Ph.D.

The Ruoff Group

Dr. John Ruoff has been involved in redistricting since the mid-1980s. He has drawn and evaluated maps for every level of single-member districts in South Carolina, from boards of public works to the U.S. Congress, including the last three rounds of statewide redistricting. He has testified and consulted as an expert in redistricting and Voting Rights court cases.



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