America’s democracy is under threat. President Trump smashes alliances, upends norms and tramples the Constitution. So it’s normal to ask: What can one citizen do to help put America on a healthier course?

I have some hard experience with this question. Back in the early part of the first Trump term, I asked myself that question and decided to try to do more. I accepted a 50 percent pay cut from The Times and, among other things, helped start a nonprofit called Weave: The Social Fabric Project. Those of us who launched it figured that social distrust is the underlying problem ripping society apart, but that trust is being rebuilt on the local level by people serving their own communities, people we call Weavers. We wanted to support them in every way.

The work was humbling. I learned that my life as a writer did not prepare me to run an organization — I’m not good at management. I made some boneheaded decisions that led to some public humiliation. Eventually The Times sensibly decided that I couldn’t work as a journalist as well as at a nonprofit that was funded by foundations and rich donors.

So I stepped back from the day-to-day at Weave and now serve in a nonpaying role as chair. But these painful experiences did have some upsides. First, under the leadership of Fred Riley and the current team, Weave is thriving. We have plans to be operating in 75 communities within three years. Second, Weave reminded me why I went into journalism. My job there was to travel around the country, interview Weavers in Nebraska, Louisiana, North Carolina and beyond and tell their stories.

I was immersed in the life of every nook and cranny of this country, and I’ve tried to keep that going to this day. I still spend more than half the year in hotel rooms somewhere.

This experience has produced in me one central conviction about what ails America: segregation. Not just racial segregation — which at least in schools is actually getting worse — but also class segregation. I’m constantly traveling between places where college grads dominate and places where high school grads dominate, and it’s a bit like traveling between different planets.

Back in 2003, Theda Skocpol of Harvard published a book called “Diminished Democracy.” One of her arguments was that more Americans used to join cross-class community organizations like the Rotary or the Elks clubs. But gradually, highly educated people left them for professional organizations filled with others more like themselves. Skocpol wrote: “Once highly educated Americans would have been members and leaders of such cross-class voluntary federations. Now many barely know about them.”

That self-segregation was symptomatic. Many college-educated people were at the same time segregating themselves in neighborhoods where nearly everybody had college degrees into professions where everybody did, into social circles in which you can go weeks without meeting somebody from the working class. Last year a group of researchers published a study in the journal Nature in which they surveyed leaders in 30 fields, including law, media, politics and so on. They found that not only had nearly all of society’s power brokers gone to college, 54 percent of them went to the same 34 elite schools. That’s segregation on steroids.

Those of us in the college-educated class are good at segregating ourselves from others, but we’re astoundingly good at segregating our kids — simply by equipping them to join our ranks. Before kindergarten, the children of the affluent are much more likely to be in preschool. By sixth grade, students in the richest school districts are four grade levels above children in the poorest school districts. By high school, richer kids’ average reading skills are five years ahead of poorer kids’. By college, according to a 2017 study led by Raj Chetty, children from the richest 1 percent of earners were 77 times more likely to go to Ivy League schools than children from families making $30,000 a year or less. In his 2019 book, “The Meritocracy Trap,” Daniel Markovits writes that the academic gap between the affluent and less affluent is greater today than the achievement gap between white Americans and Black Americans in the final days of Jim Crow.

I’d like to let that sink in. Nearly all of us were raised on the conviction that Jim Crow was rancid. We’ve effectively recreated it on class lines.

So you may want to stand up and be part of the resistance to Trump. More power to you. I myself have called for this. But let’s be clear that resistance is treating the symptom, not the ailment. The ailment is the tide of global populism that has been rising across the developed world for years, if not decades. And the cause is that our societies have segregated into caste systems, in which almost all the opportunity, respect and power is concentrated within the educated caste and a large portion of the working class understandably wants to burn it all down.

I’m somewhat worried about what Trump will do to America over the next three years. But I’m really worried about what will happen if global populism dominates the world for the next generation. What if this political climate lasts for the rest of our lives?

Similarly, I’m somewhat interested in the ways Trump’s opponents will resist his power grabs. But I’m more interested in what reforms Democrats can offer to change the underlying conditions that produced Trumpism. So far, I’m not seeing many.

School reform was an attempt to disrupt the caste system, to widen opportunity for the less privileged. Presidents Bill Clinton and Barack Obama angered core Democratic constituencies like teachers unions in order to expand opportunity down the income scale. But now Democrats have basically given up. Joe Biden didn’t devote much energy to education reform. Kamala Harris ran for president without anything like a robust education reform agenda.

Research by the Thomas B. Fordham Institute’s Michael Petrilli has demonstrated that red states are now much more active than blue states in adopting new education reform ideas. As a result, red states are leaping out ahead when it comes to student performance. The biggest education story of the last few years has been the so-called Southern surge, the significant rise in test scores in states such as Mississippi, Alabama, Louisiana and Tennessee.

In sector after sector, Democrats are in danger of becoming the party of the status quo. Here’s how it’s happening: Trump goes after some institution, like D.E.I., the federal bureaucracy or universities. The resistance folks rise up to defend those institutions without acknowledging that there’s usually a kernel of truth behind Trump’s critiques; they don’t want to give him that win, so they end up defending the institutions up and down the line. Trump ends up looking like the change agent and the resistance looks like the defenders of the past.

In my view, those of us who oppose Trump have two jobs: to resist and reform — to resist Trump and to reform the systems that cause Trumpism. The reform part is by far the most important mission, and the reforms should have one aim: to disrupt the caste system.

That will require policy reform — directing investments, as Biden began to do, into those job categories that don’t require college degrees. It will require institutional reform. Many of us work in sectors where there is very little room for Trump supporters — in media, nonprofits, the academy, the arts world. That segregation has to end.

Mostly it will require ground-up social reform. The rest of us can do something pretty simple: join more cross-class organizations and engage in more cross-class pastimes. Even something small makes a difference. This summer I’ve been wearing a New York Mets hat. As is their wont, the Mets have been trampling all over my heart for the past few months. But over that time, in places all around America, I’ve had scores of people from all walks of life come up to me to talk about the Mets, which often leads to conversations about other things. My Mets hat has reminded me of a nice reality: We still could be one nation, despite all the ways we’ve segregated it up.

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