Changing Precinct Boundaries: Who Is Affected and Electoral Consequences

We examine changes to 175,311 precincts between the 2016 and 2020 general presidential elections. Our data are the result of a unique effort to collect precinct boundaries that has never been accomplished before: on a national scale across multiple elections. We observe that precincts that underwent major changes – beyond minor changes that are generally reflective of city and town annexations affecting small populations – contain a greater share of Hispanic and Black residents and are more likely to be found in denser population areas than those that do not change. We find precincts that underwent major changes on average experienced slightly lower turnout rate increases in 2020 than those that did not change.