A post-election study by Priorities USA, a Democratic super-PAC that supported Clinton, found that in 2016, turnout decreased by 1.7 percent in the three states that adopted stricter voter ID laws but increased by 1.3 percent in states where ID laws did not change. Wisconsin’s turnout dropped 3.3 percent. If Wisconsin had seen the same turnout increase as states whose laws stayed the same, “we estimate that over 200,000 more voters would have voted in Wisconsin in 2016,” the study said. These “lost voters”—those who voted in 2012 and 2014 but not 2016—”skewed more African American and more Democrat” than the overall voting population. Some academics criticized the study’s methodology, but its conclusions were consistent with a report from the Government Accountability Office, which found that strict voter ID laws in Kansas and Tennessee had decreased turnout by roughly 2 to 3 percent, with the largest drops among black, young, and new voters.

According to a comprehensive study by MIT political scientist Charles Stewart, an estimated 16 million people—12 percent of all voters—encountered at least one problem voting in 2016. There were more than 1 million lost votes, Stewart estimates, because people ran into things like ID laws, long lines at the polls, and difficulty registering. Trump won the election by a total of 78,000 votes in Michigan, Pennsylvania, and Wisconsin.

In Wisconsin, the intent of those who pushed for the ID law was clear. On the night of Wisconsin’s 2016 primary, GOP Rep. Glenn Grothman, a backer of the law when he was in the state Senate, predicted that a Republican would carry the state in November, even though Wisconsin had gone for Barack Obama by 7 points in 2012. “I think Hillary Clinton is about the weakest candidate the Democrats have ever put up,” he told a local TV news reporter, “and now we have photo ID, and I think photo ID is going to make a little bit of a difference as well.”