Who benefits from voter identification laws?

In the first two decades of the twenty-first century, many American state governments implemented voter identification (ID) laws for elections held in their states. These laws, which commonly mandate photo ID and/or require significant effort by voters lacking ID, sparked an ongoing national debate over the tension between election security and access in a democratic society. The laws' proponents-primarily politicians in the Republican Party-claim that they prevent voter fraud, while Democratic opponents denounce the disproportionate burden they place on historically disadvantaged groups such as the poor and people of color. While these positions may reflect sincerely held beliefs, they also align with the political parties' rational electoral strategies because the groups most likely to be disenfranchised by the laws tend to support Democratic candidates. Are these partisan views on the impact of voter ID correct? Existing research focuses on how voter ID laws affect voter turnout and fraud. But the extent to which they produce observable electoral benefits for Republican candidates and/or penalize Democrats remains an open question. We examine how voter ID impacts the parties' electoral fortunes in races at the state level (state legislatures and governorships) and federal level (United States Congress and president) during 2003 to 2020. Our results suggest negligible average effects but with some heterogeneity over time. The first laws implemented produced a Democratic advantage, which weakened to near zero after 2012. We conclude that voter ID requirements motivate and mobilize supporters of both parties, ultimately mitigating their anticipated effects on election results.