In 1985, the pollster Stanley Greenberg went to Macomb County, Mich., to figure out how a traditionally Democratic suburban area could have delivered a landslide for Ronald Reagan. Last year, he was back with a similar question: How could voters in a county that turned out twice for Barack Obama have defected in such large numbers that they arguably delivered Michigan to Donald Trump?
The research zeroed in on white Trump voters without a bachelor’s degree who were either Democrats or independents and had voted for Mr. Obama at least once. Focus groups detected the same underlying theme that had motivated the Reagan Democrats more than 30 years before: a view of America as divided between “us” — white, struggling and aggrieved — and a nonwhite “them.”
In 1985, “them” meant blacks across Eight Mile Road in Detroit. Last year, they were mostly immigrants, according to a study of the results by Democracy Corps, a nonprofit that Mr. Greenberg co-founded. Among whites, they both inspired a sense of betrayal and more than a little dread.
In a place that is more than 80 percent white, Mr. Trump’s Democrats share “pretty powerful feelings about race, foreignness and Islam that lead them to see white people as victims in a country feeling increasingly foreign to many of them,” the study noted.
This persistent sense of threatened white identity raises a prickly question about the country’s direction. Mr. Trump’s rise to the presidency prompted widespread efforts to understand the motivations of the white working-class voters who propelled him into the White House. It fueled scorching debates over the role that racism played in the presidential election.
Economists proposed that workers in distress because of trade and technological shocks would embrace more nativist politicians. In one study, David Autor of the Massachusetts Institute of Technology, along with several other researchers, concluded that counties whose workers were more exposed to Chinese imports have shifted notably toward the right in presidential and congressional elections since the turn of the century.
And yet some political scientists do not entirely buy the arguments. Diana C. Mutz of the University of Pennsylvania rejects the “economic hardship” idea to explain the 2016 election, proposing instead something called “status shock.” White voters fell for Mr. Trump, she argued, because they felt threatened by increasing numbers of minorities and the sense that the United States was losing its global dominance.
Whether Mr. Trump’s proposed barriers against imports and immigrants found support because of a sense of racial threat or out of distress over the loss of manufacturing jobs to China and other countries, ethnic unease is clearly shaping American politics and policy.
The share of America defined as white and non-Hispanic is shrinking. The United States is expected to reach “minority-majority” status in the early 2040s. A Cornell University sociologist, Daniel T. Lichter, suggests that if the demographic profile of poverty remains constant, by 2050 over 70 percent of America’s poor will be from today’s minority groups.
As the American demographic profile continues to shift, pitting a shrinking population of older, non-Hispanic whites against growing cohorts of younger and poorer minorities, will many whites continue to support a liberal America — comfortable with globalization, open to trade and immigration? Or will they deploy their considerable political power to stop it?
“No other factor predicted changes in white partisanship during Obama’s presidency as powerfully and as consistently as racial attitudes,” noted John Sides, a political scientist at George Washington University.
Even those most opposed to liberal trade, he said, were hardly more likely to vote for Mr. Trump than they were four years earlier to vote for the Republican nominee, Mitt Romney, a free-trade advocate. Voters with the most negative feelings about blacks, Muslims and immigrants, by contrast, shifted their vote toward the Republican candidate.
Professor Mutz and her colleague Edward D. Mansfield suggest that racial mistrust is a critical determinant of people’s feelings about globalization. According to their work, whites prejudiced against other ethnic groups tend to believe that the United States is superior to other countries and that it should refrain from engagement in world affairs.
With whites insecure about their hold on power, be it because of China’s rise or increasing racial diversity, their support for globalization has wavered. “For white Americans, the political consequences of racial and global status threat seem to point in similar directions with respect to issue positions: opposition to immigration, rejection of international trade relationships and perceptions of China as a threat to American well-being,” Ms. Mutz wrote.
What’s more, the white voters who subscribed to Mr. Trump’s indictment of trade policies are also cold to the idea of building a safety net that might protect them from the ravages of globalization. Research by Ruy Teixeira and Robert Griffin found that 83 percent of Mr. Trump’s voters — compared with 29 percent of Hillary Clinton’s — argued that in a minority-majority nation, nonwhite groups would demand too many public services.
Shahrzad Sabet, a political scientist at the University of Maryland, notes that people who are reminded of the demographic shift tend to support more conservative positions even on race-neutral issues such as oil drilling and funding for the military.
Over the long term, diversity may increase the political support for globalization. Demographic change does not threaten minorities as it does white Americans. They never held whites’ position of power. For Hispanics and Asian-Americans, specifically, demographic change translates as more clout. Research by Ms. Mutz finds that minorities view trade and international outsourcing much more favorably than white Americans do.
Andrew J. Cherlin, a sociologist at Johns Hopkins University, suggests that demographic change will most likely relax racial and ethnic divisions. Not only is intermarriage rising, but current racial definitions are also unlikely to hold. The question is what is going to happen between now and then.
“There might be a period coming up where some whites resist the expansion of the concept of majority,” Mr. Cherlin acknowledged.
Ms. Mutz detects an increase in white Americans’ sense of threat between 2012 and 2016, probably linked to the presence of a black president. Benjamin Enke, an economist at Harvard University who studies the evolution of cultural biases, also suggests that feelings of “us” versus “them” may be on the rise.
Politicians’ appeals to voters’ communal morality — characterized by their sense of group loyalty rather than support for universal values — have been rising in this century, he reports. And this tribal ethic also seems to be rising in the general population. Mr. Enke notes that communal morality has been gaining ground since 2010 among conservatives responding to an online questionnaire about moral foundations.
To what extent could policy break down the barriers of ethnic hostility and mistrust? A good economy would help. Racial differences rise to the top of voters’ minds when the economy falters, heating up both the competition for jobs and the debate over the use of tax dollars. By contrast, economists suggest, racial attitudes take a back seat in better economic times.
Mr. Greenberg’s pollsters visited Macomb County in 2008, too. Race and immigration didn’t come up nearly as stridently then. Voters’ anger was directed primarily at corporations, so willing to send jobs offshore, rather than at minorities.
“Had I administered a test on racism, they would have scored badly,” Mr. Greenberg told me. “I’m sure their racial identity was just as strong in 2008 and 2012, but despite those attitudes they voted for Obama twice.”
But though Macomb’s voters may prove that race does not necessarily beat every other card, their evolution suggests that voting based on racial fears is not going to disappear soon.
One lesson of the 2016 election is that it is easy to exploit racial mistrust, xenophobia and ethnic hostility for political gain.