All legislative districts – congressional, state legislative, and local – must comply with the fundamental principle of “one person, one vote.” This is achieved by drawing districts with relatively equal populations, using data from the US Census Bureau. But this principle is undermined by the practice of prison gerrymandering, which arises because of the way in which the Bureau counts incarcerated individuals. Unlike students away at boarding school or deployed members of the military, incarcerated people are counted at the facilities in which they are confined, rather than their home communities. Moreover, they are counted as residing at the facility for the next decade, regardless of their sentence length. As a result, these individuals will be counted as part of the district’s population where their facility is located – despite rarely having the opportunity to vote on their elected officials.

In the 2021 redistricting cycle, 13 states took steps to address this problem by implementing prison gerrymandering reforms. Since then, two more states have adopted reforms in advance of the 2031 cycle, and numerous localities have abolished the practice at the local level. Although the exact reforms differ, the general solution is to count incarcerated people at their last known address. The nonpartisan Redistricting Data Hub has analyzed the implementation and impact of these reforms in a national report. The report gives a detailed breakdown of how policy choices affect the number of incarcerated people ultimately counted at home, and estimates that 852,000 more people would be counted at home if all states adopted similar reforms.

Utilizing data from Rory Kramer, Brianna Remster, and Denise Wilson of Villanova University, the Redistricting Data Hub has also produced a series of reports to help advocates, researchers, and citizens understand the problem in 10 states without reforms. These reports use last known residency and sentencing data to estimate where incarcerated people come from and how current practices impact congressional and state legislative districts. Reports in additional states or updated in states with mid-decade redistricting may be made available on request from: help@redistrictingdatahub.org.