The Impact of Vote-By-Mail Policy on Turnout and Vote Share in the 2020 Election

Abstract

The COVID-19 pandemic spurred many states and counties to reduce public health risks by adopting policies that made voting by mail easier in the 2020 general election. Employing a two-period difference-in-difference research design, this article investigates how these policy changes affected turnout and presidential vote share. We find that counties that moved to send registered voters mail-in ballots ahead of Election Day experienced 2.6 percent higher turnout compared to counties that made no change, although lesser reforms may have hindered turnout. We also find no evidence that making voting by mail easier conferred a partisan advantage.