Universal Vote-by-Mail Has No Impact on Partisan Turnout or Vote Share

Abstract

In response to COVID-19, many scholars and policymakers are urging the U.S. to expand voting-by-mail programs to safeguard the electoral process. What are the effects of vote-by-mail? In this paper, we provide a comprehensive design-based analysis of the effect of universal vote-by-mail—a policy under which every voter is mailed a ballot in advance of the election—on electoral outcomes. We collect data from 1996-2018 on all three U.S. states who implemented universal vote-by-mail in a staggered fashion across counties, allowing us to use a difference-in-differences design at the county level to estimate causal effects. We find that: (1) universal vote-by-mail does not appear to affect either party’s share of turnout; (2) universal vote-by-mail does not appear to increase either party’s vote share; and (3) universal vote-by-mail modestly increases overall average turnout rates, in line with previous estimates. All three conclusions support the conventional wisdom of election administration experts and contradict many popular claims in the media.

Publication
Forthcoming, PNAS
Jennifer Wu
Jennifer Wu
Research Fellow
Jesse Yoder
Jesse Yoder
4th year PhD Student

Graduate Student at Stanford University

Andy Hall
Andy Hall
Professor of Political Science

Professor of Political Science at Stanford University