Strict ID Laws Don’t Stop Voters: Evidence from a U.S. Nationwide Panel, 2008–2018
基于16亿观测值的面板数据，采用双重差分法发现美国严格选民身份法对整体或任何群体的登记率和投票率无负面影响，但可能通过政党动员抵消对少数族裔的微弱影响。
Abstract U.S. states increasingly require identification to vote—an ostensible attempt to deter fraud that prompts complaints of selective disenfranchisement. Using a difference-in-differences design on a panel data set with 1.6 billion observations, 2008–2018, we find that the laws have no negative effect on registration or turnout, overall or for any group defined by race, gender, age, or party affiliation. These results hold through a large number of specifications. Our most demanding specification controls for state, year, and voter fixed effects, along with state and voter time-varying controls. Based on this specification, we obtain point estimates of −0.1 percentage points for effects both on overall registration and turnout (with 95% confidence intervals of [−2.3; 2.1 percentage points] and [−3.0; 2.8 percentage points], respectively), and +1.4 percentage points for the effect on the turnout of nonwhite voters relative to whites (with a 95% confidence interval of [−0.5; 3.2 percentage points]). The lack of negative impact on voter turnout cannot be attributed to voters’ reaction against the laws, measured by campaign contributions and self-reported political engagement. However, the likelihood that nonwhite voters were contacted by a campaign increases by 4.7 percentage points, suggesting that parties’ mobilization might have offset modest effects of the laws on the participation of ethnic minorities. Finally, strict ID requirements have no effect on fraud, actual or perceived. Overall, our findings suggest that efforts to improve elections may be better directed at other reforms.