Automatic Voter Registration as a Housewarming Gift: Quantifying Causal Effects on Turnout Using Movers

How much does automatic voter registration (AVR) increase turnout? Unlike many democracies, American voters in many states face additional costs of registration, resulting in potential disenfranchisement. AVR is expected to promote turnout by alleviating registration costs, but its causal effects have rarely been quantified due to violations of crucial assumptions. I show that automatic voter (re)registration increases turnout by 5.8 percentage points by exploiting a discontinuity in a novel dataset of voters who moved. Election officials in Orange County, California, notified existing registrants who moved that their residential addresses were automatically updated. The treatment alleviated registrants of re-registration burdens--but only for those who moved before the legal cutoff date. Contrary to the popular narrative, AVR had no significant effect on the turnout of registered Democratic voters, but Republicans' and nonpartisans' turnout increased by 8.1 and 7.4 percentage points.