Partisanship is Why People Vote in Person in a Pandemic

Objective: The choice of voting methods has increasingly become a politicized, partisan issue. We ask: can a nationalized partisan rhetoric cast doubt on vote-by-mail (VBM) despite years of experience and a raging pandemic? Methods: Using 2020 general election records in Colorado, an established all-mail voting state, we analyze first the general choice of voting methods using supervised machine learning and then the choice to switch to in-person voting despite having used VBM in previous cycles. Results: The choice of voting modes is mainly habitual; local variations of COVID-19 hardly mattered. Republican partisanship played an important role in predicting "switchers" to in-person voting; the probability was 5.2% conditional on being a Republican as opposed to 1.9% for a Democrat. Conclusion: The results suggest that voting in person can be heavily polarized by partisan communication, despite being a health behavior in a pandemic and voters having experience with mail voting.