Postal delivery disruptions and the fragility of voting by mail: Lessons from Maine

Abstract

Since the onset in early 2020 of the COVID-19 pandemic in the United States, mail-in voting rates in states that have held elections have surged, presumably reflecting the fact that voting by mail is a relatively safe mode of ballot casting during a public health crisis. Matters of health notwithstanding, postal delivery disruptions can place mail-in ballots at risk of rejection on the grounds of lateness. With Maine as a case study, we show that, in the past four general elections, over 10% of vote-by-mail ballots arrived at local elections offices either on Election Day itself or one day earlier. Moreover, of the vote-by-mail ballots most vulnerable to postal delivery disruptions, a greater share of them were cast by unaffiliated voters and Democrats than by Republicans. Our results highlight the fragility of voting by mail in light of concerns about the reliability of the United States Postal Service. While existing research shows that the opportunity to vote by mail is neutral with respect to partisanship, our results highlight an aspect of mail-in balloting that nonetheless has a partisan hue—the extent to which vote-by-mail ballots are vulnerable to mail delays.