Here are the studies:
A study by the University of Missouri on turnout in Indiana showed that turnout actually increased by about 2 percentage points overall in Indiana in 2006 in the first election after the voter ID law went into effect.[17] There was no evidence that counties with higher percentages of minority, poor, elderly, or less-educated populations suffered any reduction in voter turnout. In fact, "the only consistent and statistically significant impact of photo ID in Indiana is to increase voter turnout in counties with a greater percentage of Democrats relative to other counties."[18]
• In September 2007, The Heritage Foundation released a study analyzing the 2004 election turnout data for all states. This study found that voter ID laws do not reduce the turnout of voters, including African–Americans and Hispanics. Such voters were just as likely to vote in states with ID as in states where just their names were asked at the polling place.[19]
• A study by the University of Delaware and the University of Nebraska–Lincoln examined data from the 2000, 2002, 2004, and 2006 elections. At both the aggregate and individual levels, the study found that voter ID laws do not affect turnout, including across racial/ethnic/socioeconomic lines. The study concludes that "concerns about voter identification laws affecting turnout are much ado about nothing."[20]
• A survey by American University of registered voters in Maryland, Indiana, and Mississippi to see whether registered voters had photo IDs concluded that "showing a photo ID as a requirement of voting does not appear to be a serious problem in any of the states" because "[a]lmost all registered voters have an acceptable form of photo ID."[21] Less than 0.5 percent of respondents had neither a photo ID nor citizenship documentation. A 2008 election survey of 12,000 registered voters in all 50 states found that fewer than nine people were unable to vote because of voter ID requirements.[22]
• In 2010, a Rasmussen poll of likely voters in the United States showed overwhelming support (82 percent) for requiring photo ID in order to vote in elections. This support runs across ethnic and racial lines; Rasmussen reports that "[t]his is a sentiment that spans demographics, as majorities in every demographic agree."[23]
• A similar study by John Lott in 2006 also found no effect on voter turnout and, in fact, found an indication that reducing voter fraud (through means such as voter ID) may have a positive impact on voter turnout.[24]