Vote-by-mail policy and the 2020 presidential election

Mail voting became unusually controversial in the 2020 presidential election. Many observers, including former President Trump, believed that more accessible vote by mail would encourage higher turnout at the expense of Republicans. While the literature has tested some of these claims, it has not offered a more comprehensive causal assessment of vote-by-mail policy, nor has any study looked at these questions in the context of the extraordinary 2020 election. We examine the effect of mail ballot access policies both before and during the 2020 pandemic election with county-level data and a variety of methodological approaches. Our results suggest that making it easier to vote by mail—especially mailing every voter a ballot—generally does increase turnout, both before and during the 2020 election. By contrast, the same policies do not have robust partisan effects, and in many models, they tilt the results in a more Republican direction. While some of our findings are sensitive to model specification, the positive turnout effect of mailing every voter a ballot is robust to many alternative approaches. The confirmation of the existing understanding of universally mailed ballots suggests the basic dynamics of the reform are immune to a wide range of disruptive forces.