Charles Stewart has posted this important draft on SSRN. Here is the abstract:
A “lost vote” occurs when a voter does all that is asked of her, and yet her vote is uncounted in the final tally. Estimating the magnitude of lost votes in American presidential elections has followed the work of the Caltech/MIT Voting Technology Project, which initially estimated the magnitude of lost votes in the 2000 presidential election, due to failures of voter registration, polling-place management, and voting technologies, to be between 4 and 6 million out of 107 million cast that year. Because of data and conceptual limitations, lost vote estimates have tended to focus on in-person voting, ignoring lost votes due to mail voting. This paper revisits the one previous effort to estimate lost votes, by considering data available from the 2016 presidential election. Conceptually, the paper highlights how differing mail-ballot legal regimes produce lost mail votes in different ways, and at different rates, on account of differing laws, regulations, and practices. Empirically, the paper draws on administrative records and surveys to provide an estimated number of lost mail votes in 2016. That estimate works out to approximately 1.4 million votes in 2016—4.0% of mail ballots cast and 1.0% of all ballots. These estimates are relevant in light of efforts to expand mail balloting in the 2020 presidential election. States that will see the greatest growth in mail ballots tended to have higher lost vote rates than those with vote-by-mail systems. This implies that a doubling or tripling of the number of mail ballots in 2020 will result in a disproportionate growth in the number of lost votes due to mail ballots.