2016 Postmortem

The data implies that Mr. Obama was not as weak among white voters as typically believed. He fared better than his predecessors among white voters outside the South. Demographic shifts weren’t so important: He would have been re-elected even with an electorate as old and white as it was in 2004. Latino voters did not put Mr. Obama over the top, as many argued in the days after Mr. Obama’s re-election. He would have won even if he had done as poorly among Latino voters as John Kerry.

The larger number of white working-class voters implies that Democrats are far more dependent on winning white working-class voters, and therefore more vulnerable to a populist candidate like Mr. Trump.

Over all, 34 percent of Mr. Obama’s supporters were white voters without a college degree, compared with 25 percent in the exit polls, according to an Upshot statistical model that integrated census data, actual results and 15,000 interviews from various pre-election surveys. The model yields a full alternative to the exit polls that assume an older, whiter electorate like the one depicted by the census. (For those interested in the details about our estimates, we’ve written a technical sidebar.)

Mr. Obama’s dependence among white voters might seem surprising in light of the 2012 postelection consensus. But it won’t be surprising if you think just a little further back — to the pre-election story line. Mr. Obama’s advantage heading into the election was thought to be a “Midwestern Firewall” — a big edge in Midwestern battlegrounds where white working-class voters supported the auto bailout and were skeptical of Mr. Romney, who was criticized for his time at Bain Capital.

The pre-election story line was tossed aside when the national exit polls showed an electorate that was even more diverse than it was in 2008, while showing Mr. Obama faring worse among white voters than any Democrat since Walter Mondale in 1984.

But the Upshot analysis shows that all of Mr. Obama’s weaknesses were in the South — defined as the former Confederacy plus Oklahoma, Missouri, Kentucky and West Virginia — where he won just 26 percent.

Outside the South, he won 46 percent of white voters, even running ahead of Mr. Kerry and Al Gore in earlier elections.