But the new Census numbers on voter participation last year also contain a clear warning signal for Democrats. While the overall U.S. population continues to grow more racially and ethnically diverse, the electorate’s demographic transformation slowed markedly in 2016 because turnout remained surprisingly weak among Hispanics and fell sharply among African Americans without former President Barack Obama on the ballot, according to the findings.

Though minority voters preferred Hillary Clinton by a large margin, those disappointing turnout numbers underscore the difficulty she had mobilizing the Democratic coalition around a message that placed much more emphasis on values and tolerance—so-called “identity politics”—than a bread-and-butter economic message.

“The long-term challenge for Republicans remains unchanged: They still have to figure out how to appeal to the growing proportion of the electorate that is non- white and college-educated,” said GOP pollster Whit Ayres, who worked during the Republican primaries for Trump rival Marco Rubio, the Florida senator. “Trump managed to slip the punch for one election, but that changed nothing about the long-term challenge. For the Democrats … they have to [find] a substantive message that appeals beyond identity politics, and they haven’t figured that out yet.”

Always important, shifts in the electorate’s composition have become even more critical to election outcomes as the distance has widened between the preferences of key groups. Republicans now routinely amass wide margins among whites without a college degree, with exit polls showing Trump establishing the biggest advantage of any GOP nominee since Ronald Reagan in 1984. Democrats consistently dominate among non-white voters. And whites with a college degree usually lean toward Republicans, though much less lopsidedly than their blue-collar counterparts. As both candidate and president, Trump has faced much more resistance among well-educated whites than Republicans usually confront.

There is no single authoritative source on the electorate’s makeup. The two most widely cited are Census data, gleaned from the Current Population Survey, and the Election Day exit polls conducted outside polling places around the country by Edison Research for a consortium of news organizations. Political professionals increasingly rely on detailed studies of state voter files for a third perspective on which Americans voted, although those sources are not as widely available to the public.

The main difference between the two principal public sources is that the exit polls consistently identify whites with at least a four-year college education as a larger share of the vote—and whites without a degree as a considerably smaller share—than the Census does. In a much smaller disparity, the exit polls also regularly find minorities constituting a slightly larger share of the vote than the Census does.