Chris Arnade, left Wall Street and began photographing the “back-row kids” across the United States. (Courtesy of Chris Arnade)

The best way to get photographer Chris Arnade to go somewhere is to warn him not to.

Hunts Point in the Bronx is dangerous; stay away, friends said, when Arnade began walking all over New York City with his camera.

That was when Arnade, now 51, was still a Wall Street bond trader, years before he would find himself documenting what he thinks of as Donald Trump’s America: the poor or working-class people left behind by the economic recovery.

As Arnade became frustrated by the values of Wall Street, especially after the 2008 financial meltdown and bailout, he began wandering the city — sometimes on “terminus walks,” in which he would take a subway line to its endpoint and walk back home, often many miles.

He went to Hunts Point, over and over again, documenting the lives there, especially addicts and prostitutes.

It was “full immersion,” he said, even to the point of giving his subjects money that he knew would go to buy drugs. Although it wasn’t very long ago, less than a decade, it was before he considered himself a journalist. He says he wouldn’t do that now, but back then, “it was just a personal project.”

His work, mostly self-published, drew plenty of criticism. Some photographers and community members found his methods exploitive and thought his sometimes sordid images were unfair to the multifaceted Bronx.

“What he did was very limited and wrong,” said Rhynna M. Santos, a documentary photographer and founder of the Bronx Women’s Photo Collective.

But he kept going, sometimes getting his photographs and his writing published, including in the Guardian and the Atlantic, but mostly relying on personal funds. (Arnade’s former Guardian editor, media consultant Heidi Moore, calls him brilliant and praises his “strong moral center.”)

After taking a buyout from Citigroup in 2012, he branched out far beyond New York, traveling in short spurts and putting tens of thousands of miles on his 2006 Honda Odyssey (now at 265,000 miles) with its back seats removed to accommodate a mattress.

Arnade sought the poor or unfashionable areas in every location, whether Worcester, Mass.; Utica, N.Y.; Bridgeport, Conn.; Baltimore; or El Paso.

By the summer of 2015, shortly after Trump declared his candidacy, something remarkable was happening.

“Everybody I talked to wanted to vote for Trump,” he said. “There was a big disconnect between what you’d see in the press and what I’d hear on the ground.”

He kept going: Buffalo. Kingston, Tenn. Milwaukee. Selma, Ala. He would find the McDonald’s in the poor part of town, or the Walmart parking lot, places he described as ad hoc community centers.

“I didn’t have the name or the pedigree. I was just a guy in a car with a camera,” he said. (He does have a PhD in physics from Johns Hopkins University, earned at a time when brainy science types with high mathematical capability — “quants” — were getting hired by Wall Street firms like Salomon Brothers, where Arnade went to work.)

On the night Donald Trump accepted the Republican presidential nomination, Arnade was near Cleveland — as were thousands of journalists. Unlike most of them, though, he was nowhere near the convention hall.

“For the speech, I was in a strip club in Parma,” a working-class Cleveland suburb. He recalled the jubilation around him: “a bunch of people bitching about the world and loving Trump.”

That was no big surprise to Arnade — and neither were the election results last month. Back in May, when many were still pooh-poohing Trump’s chances, Arnade wrote a notable series of tweets: If Trump didn’t win this time around, it would only be because he was such a deeply flawed candidate; but some Trumplike figure soon would capi­tal­ize on people’s anger and disenfranchisement.

“I don’t like Trump, not in the least bit, but I was watching him resonate,” said Arnade, who says he preferred Bernie Sanders.

These days, Arnade is no longer a resident of upscale Brooklyn Heights; he moved his family of five upstate to New Paltz.

Arnade has little confidence that Trump will actually address the economic and cultural inequality that helped to power his appeal. And, to be sure, enthusiasm from left-behind Americans is far from the full story of Trump’s triumph.

But Arnade saw the emotions up close: “You have to put people’s decisions in context — how distant they are from the money. The media wasn’t getting this. The politicians weren’t getting it.”

Democratic nominee Hillary Clinton, he said, “represented the front row” — the smartest students in class, destined to enjoy the money and status that came with silver-spoon success.

For what Arnade calls the “back-row kids,” the frustration, anger and, yes, humiliation had become overwhelming.

Trump zeroed in, Arnade said, on the one thing that mattered most: The system is rigged against them. They had no shot at achieving the American Dream.

“You had hope leaving . . . and then Trump’s message coming in,” he said.

Arnade said his time on the road, which continues, has changed him.

“I learned to get rid of my education,” he said. “I had to stop being the guy who always says, ‘Well, actually . . .’ to prove I know better.”

It’s a lesson worth learning.

For more by Margaret Sullivan, visit wapo.st/sullivan