Why did Trump win?

Why did Trump win — and Clinton lose — the 2016 U.S. presidential election? That’s been debated widely, to understate the case. Nominees include each campaign’s ground game, messaging, FBI Director James B. Comey’s last-minute letter to Congress, and defections from the “Obama coalition.”

Here, we offer new data to show that shifts in which racial groups went to the polls may have made the difference.

Using data from the voter file vendor Catalist and information from the U.S. Census Bureau, we examine the change in turnout rates for different racial/ethnic groups between 2012 and 2016. Black turnout declined dramatically; white turnout increased noticeably; and Latino and Asian American turnout went up even more. In the key swing states of Michigan, Wisconsin, and Pennsylvania, those shifts were especially strong. How strong? Without those shifts in turnout from various racial and ethnic groups, these pivotal states might have gone not to Trump but to Clinton — giving Clinton an electoral college victory.