Should I vote-by-mail or in person? The impact of COVID-19 risk factors and partisanship on vote mode decisions in the 2020 presidential election.

While the evidence is clear that 2020 voters shifted away from Election Day voting in favor of vote-by-mail and early voting, we know very little about how health risk versus party polarization around risk assessment influenced how and when to vote. We rely on individual-level observational data in the form of high-quality official voter administrative records from the State of New Mexico to ask how pandemic-related risk factors, especially voter age along with partisanship influenced voter decision-making. To identify causal factors, we use a difference-in-differences design and hazard model that compare 2020 general election and primary voter behavior to 2018 and 2016. We find that age and party were large factors in vote mode decisions in 2020, but not in 2016 or 2018. We consider the implications of our findings on how health risk and partisanship interact to influence decision-making.