Mason believes that even though growing numbers of those with mixed parentage think of themselves as white, many other whites are not currently prepared to accept that claim:

It doesn’t matter if someone identifies as white as long as other people consider them to be nonwhite. In fact, I’d argue that the Dubois concept of the “wages of whiteness” requires that some groups NOT be white.

Bart Bonikowski, a professor of sociology at Harvard, argues that in the contemporary political climate, the fear of cultural disruption has become so pervasive on the right that realistic facts and figures make little difference. As he wrote in an email:

My sense is that actual levels of migration, shifts in immigrants’ ethnic identification, and changing rates of intermarriage are, at best, only loosely coupled with perceptions of cultural threat among white voters, particularly those with moderate levels of education and those living outside of urban centers. Even though actual levels of undocumented migration from Mexico — and net migration from that country in general — have decreased in recent years, this in no way diminished the potency of Donald Trump’s xenophobic discourse in the 2016 presidential election. Indeed, this was true despite the fact that aggregate favorability toward immigrants has been steadily increasing in the United States over the past decade.

Bonikowski elaborated:

The reason for this is that many Trump supporters have long held strong ethnonationalist sentiments, but these sentiments have only recently become politically salient, as Trump, and other Republicans before him, have actively stoked fears of demographic and cultural change and channeled them into powerful resentments toward minority groups. For many voters, such resentments are not rooted in everyday experience, not least because they tend to live in ethnically homogeneous, predominantly white communities, but rather, they are shaped by powerful nativist narratives perpetuated by right-wing politicians, partisan organizations, and media outlets.

From another vantage point altogether, William Frey, a demographer at the Brookings Institution, defended census majority-minority calculations in an email, arguing that it is important for the country to face what he has called the “diversity explosion”:

Given the slow and in fact, last year, negative growth of the white population along with its rapid aging — it is important for older whites to understand that the only way we will have a growing labor force will be to embrace the younger racial minority populations.

Frey described projections that many young people of mixed racial and ethnic backgrounds will self-identify as white as “quite speculative.” He questioned putting forth such projections

for the sole purpose of potentially appealing to Trump supporters — many of whom do not seem to be interested in other demographic facts such as last decade’s decline of undocumented immigration to the U.S., or the greater number of migrants coming from Asia than from Latin America.

Howard Lavine, a professor of political science and psychology at the University of Minnesota, staked out a middle ground, pessimistic in the short term, less so in the long term:

Intermarriage — especially among whites and Hispanics — may produce a substantial percentage of children (and grandchildren) who identify as white, but I doubt that such predictions will go far in currently assuaging the race-based status threat that many working class-whites feel today, and that Donald Trump exploited so successfully.

Over time, however, Lavine argued, as

races and cultures become less distinct (more assimilated), Republican voters who are dispositionally intolerant of difference (e.g., authoritarians) will find the political climate less threatening and the category of race per se less politically relevant.

Could a more multifaceted narrative than the binary white vs. minority projection into the future lessen the anxiety of some whites? Michael Barber, a political scientist at Brigham Young, doubts it:

The actual date at which the U.S. becomes majority-minority is probably irrelevant to the typical Trump voter or Republican in general. My guess is that perceptions matter much more than reality.

In support of his view, Barber cited an intriguing research paper. “The Parties in Our Heads: Misperceptions about Party Composition and Their Consequences,” by Douglas J. Ahler, a political scientist at Florida State University, and Gaurav Sood, then a postdoctoral fellow at Georgetown.

Their research shows, Barber writes, that partisans have extremely biased perceptions of the “other” party, including survey data showing that people “think that 32 percent of Democrats are LGBT (vs. 6 percent in reality) and 38 percent of Republicans earn over $250,000 per year (vs. 2 percent in reality).” With this in mind, Barber argued, “it isn’t a stretch to imagine that people think we’re already a majority-minority country when in fact we aren’t at all.”

Some of those I contacted suggested that only Trump and his fellow Republicans have the power to change the anti-immigrant, anti-minority tone of the political conversation. Nathan Kalmoe, a political scientist at Louisiana State University, argued, for example, that

Politicians and other opinion leaders play an important role in helping citizens make sense of the threats and opportunities they face. I expect the views of many white Americans would shift if President Trump and other leaders who deploy ethnonationalist messages collectively changed their tune, at least in terms of attitude intensity and priority.

In the highly unlikely event that that happened, “prejudices wouldn’t vanish, but they would be less politically potent for most people.” More realistically, Kalmoe wrote, “as long as prominent leaders continue to mobilize white fear and anger on the issue, citizens who trust them will follow.”

From a broader perspective, the current majority-minority controversy is a continuation of the never-ending, never-resolved struggle in this country over how to deal with a rapidly transforming multiracial, multiethnic society.

Robert Jones, the C.E.O. of the Public Religion Research Institute, put the problem this way in an email:

Throughout American history in particular, the question of whiteness has been at the center of these debates, fueled by the fact that social privileges and political rights were tied to whiteness.

Historically, this has played out in the practices of the Census Bureau and the Citizenship and Immigration Services that “recorded race and ethnicity categories over time, e.g., ‘Celt’ and ‘Hebrew’ once appeared outside of the ‘Caucasian’ category.”

Jones argues that

at the current moment in U.S. history, we actually need the admittedly fictional concept of “whiteness” to understand recent events that are driven by a motivation to defend a perceived threat to white demographic and cultural dominance: the mass murder of nine worshipers in Charleston by the Confederate flag wielding Dylann Roof, the white supremacists marching in Charlottesville chanting “you/Jews will not replace us,” and even the unlikely but unflagging support for Donald Trump among white evangelical Protestants nostalgic to resurrect the cultural world of the 1950s.

Jones captures the strength of the racial and ethnic divisions that have characterized the nation since its founding:

The troubling truth of American history is that it’s precisely the binary understanding of white vs. nonwhite that has been at the center of our bloodiest battles, harshest laws, and fiercest debates. The U.S. social and political landscape would be unrecognizable but for the power of the concept of whiteness.

It’s certainly a problem we keep coming up against.

I invite you to follow me on Twitter, @Edsall.

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