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

How much can automatic voter registration (AVR) increase turnout? Unlike in many democracies, most American voters face the additional cost of registration, resulting in potential disenfranchisement. Automatic voter registration is naturally expected to promote turnout, but its causal effects have rarely been quantified due to violations of crucial assumptions. I show that a variation of AVR that targets existing registrants as opposed to eligible nonregistrants—termed automatic reregistration (ARR)—increases turnout by 5.8 percentage points. I exploit a natural experiment in a novel administrative dataset; election officials in Orange County, California, notified existing registrants who moved within-county that their residential addresses were automatically updated. The treatment alleviated registrants of reregistration burdens, but only for those who moved before the legal cutoff date, enabling a quasi-random treatment assignment. Contrary to the popular narrative, ARR had no significant effect on the turnout of registered Democrats, but Republicans’ and nonpartisans’ turnout increased by 8.1 and 7.4 percentage points, respectively.