Measuring and mitigating voting access disparities: a study of race and polling locations in Florida and North Carolina

Abstract

Voter suppression and associated racial disparities in access to voting are long-standing civil rights concerns in the United States. A history of violent explicit discouragement has shifted to more subtle access limitations that can include long lines and wait times, long travel times to reach a polling station, and other logistical barriers to voting. Our focus in this work is on quantifying disparities in voting access pertaining to the overall time-to-vote, and how they could be remedied via a better choice of polling location or provisioning more sites where voters can cast ballots. However, appropriately calibrating access disparities is difficult because of the need to account for factors such as population density and different community expectations for reasonable travel times. In this paper, we perform one of the first large-scale studies of voter access to polling locations, using real-world voter data from Florida and North Carolina in the 2020 general election. We develop a methodology for the calibrated measurement of disparities in polling location "load"and distance to polling locations based on a novel normalized distance metric to model the voter experience of distance. We find that voter turnout is reduced when this normalized distance to polling locations increases, and that non-white voters had to travel further to the polls in Florida (using this normalized distance) than White voters. We also introduce algorithms, with modifications to handle scale, that can reduce these disparities by suggesting new polling locations from a given list of identified public locations (including schools and libraries). The developed voting access measurement methodology and algorithmic remediation technique demonstrates that better polling location placement is possible.