Does voting technology affect election outcomes? Touchscreen voting and the 2004 presidential election

Critics argue that electronic voting is vulnerable to fraud. We test whether voting technology affected electoral outcomes in the 2000 and 2004 presidential elections. We find a positive correlation between use of electronic voting and George Bush vote share. The effect could have been large enough to influence the final results in some swing states. While this pattern would appear to be consistent with allegations of voting irregularities, a closer examination suggests this interpretation is unlikely. We find no evidence that electronic voting had a larger effect in swing states, or in states with a Republican secretary of state. We also find that electronic voting has a negative effect on turnout rates of Hispanics (who tend to favor Democrats). Electronic voting was more likely to be used in counties with a higher fraction of Hispanics; especially in swing states.