After the election, registered voters in Milwaukee County and Madison’s Dane County were surveyed about why they didn’t cast a ballot. Eleven percent cited the voter ID law and said they didn’t have an acceptable ID; of those, more than half said the law was the “main reason” they didn’t vote. According to the study’s author, University of Wisconsin-Madison political scientist Kenneth Mayer, that finding implies that between 12,000 and 23,000 registered voters in Madison and Milwaukee—and as many as 45,000 statewide—were deterred from voting by the ID law. “We have hard evidence there were tens of thousands of people who were unable to vote because of the voter ID law,” he said.