How does voting equipment affect the racial gap in voided ballots?

An accumulating body of research suggests that African Americans cast invalid ballots at a higher rate than whites. Our analysis of a unique precinct-level dataset from South Carolina and Louisiana shows that the black-white gap in voided ballots depends crucially on the voting equipment people use. In areas with punch cards or optically scanned ballots, the black-white gap ranged from four to six percentage points. Lever and electronic machines, which prohibit overvoting and make undervoting more transparent and correctible, cut the discrepancy by a factor of ten. Judging from exit polls and opinion surveys, much of the remaining difference could be due to intentional undervoting, which African Americans profess to practice at a slightly higher rate than whites. In any case, the use of appropriate voting technologies can virtually eliminate the black-white disparity in invalid ballots.