It turns out that everyone underestimated how a proposal for mass deportations could bring Americans together.

Donald Trump assembled the biggest, most diverse GOP coalition in decades while running further to the right on immigration, crime and the culture than perhaps any major-party presidential candidate in U.S. history.

Trump inveighed against unchecked illegal immigration in harsh and lurid terms — and picked up Hispanic voters.

Trump pledged to reverse “a brutal plague of bloodshed, crime, chaos, misery and death in our land” — and won more young voters.

Trump famously dethroned the Republican establishment in 2016, and now has crushed its theory of how to forge a GOP future in an increasingly diverse country.

Trump may win the most electoral votes of a Republican since George H.W. Bush in 1988. In the 1980s, America was roughly 80% white, and Hispanics and Asians were less than 7% and 2% of the population respectively. Now, Hispanics and Asians are 19.5% and 6.4%, while whites have declined to 75% of the population.

We’ve long been told these changes are a herald of doom for the Republican Party, and the GOP can only survive by softening its edges.

This was the admonition of the famous “autopsy” commissioned by the Republican National Committee after Mitt Romney’s loss to Barack Obama in 2012. According to the report, the divisive policies and tone of Romney’s GOP — yes, the resolutely polite, earnest and scrupulous Mitt Romney — were sentencing the party to demographic extinction.

To win Hispanics, the autopsy insisted, Republicans “must embrace and champion comprehensive immigration reform,” the establishment’s favorite euphemism for a mass amnesty. “It does not matter,” it maintained, “what we say about education, jobs or the economy; if Hispanics think we do not want them here, they will close their ears to our policies.”

And the party’s tone had to change. The autopsy intoned that “we must emphasize during candidate trainings, retreats, etc., the importance of a welcoming, inclusive message.”

The same applied to young voters: “The RNC must more effectively highlight our young leaders and fundamentally change the tone we use to talk about issues and the way we are communicating with voters.”

Given what we now know, the autopsy could have said, “To thrive in the future, the party needs to find a forceful, charismatic leader in his late 70s who often speaks in vivid, crude terms, and sounds a lot like Pat Buchanan on the issues.”

According to the exit polls, Trump won Latino men and males age 18-29, while also gaining among Asians and black men, and holding his big edge among whites without college degrees.

Once Trump established working-class credibility on economics, the door was open to gains among Latino and African-American men who are patriotic, culturally conservative and uninterested in being considered members of a victim group. These voters aren’t easily offended, so Trump’s mode of communication doesn’t bother them.

The Biden-Harris border policies, the progressive tolerance for urban disorder, the push to implement a radical trans agenda and the priorities of woke identity politics struck so many voters as so completely mad that Trump had permission to say or do anything in opposition. It wasn’t so much Trump who made the idea of mass deportation mainstream as the Biden-Harris insistence on creating a border crisis and denying that it was happening.

Also, a crucial backdrop for Trump’s success was the broader economic discontent, as well as Joe Biden’s sheer unpopularity.

All is flux, so perhaps 2024 won’t be replicable, but, for now, Trump has shown that demographics isn’t destiny. His right-wing populism has made inroads among a broad range of voter groups, while Kamala Harris — an emblem of progressivism’s cultural obsessions — picked up among college-educated whites and among seniors.

Who looks like the future now?