The Durable Differential Deterrent Effects of Strict Photo Identification Laws

Abstract

An increasing number of states have adopted laws that require voters to show photo identification to vote. We show that the differential deterrent effect of strict ID laws on turnout, the differential effect of the laws on those without valid ID, persists even after the laws are repealed. To assess the persistent effect of ID laws on turnout we leverage administrative data from North Carolina and a photo ID law that was in effect for a primary election, but not the subsequent general election. Using exact matching and a difference-in-differences design, we show that the photo ID law caused a 1 percentage point turnout decrease for voters without a North Carolina ID law in the primary election. After the law was suspended this effect persisted: those without an ID were 2.6 percentage points less likely to turnout in the general election. The general election effect is robust to a variety of alternative explanations and we show is consistent with aggregate analyses that find a null effect of voter ID laws. Our results suggest that photo ID laws’ differential deterrent effect persists because voters lack information about the changing requirements for voting, creating confusion that deters turnout.