WASHINGTON — Nigel works three jobs to make ends meet.

He is black, single, progressive politically and determined to live the American dream — “as long, of course, that it does not kill me first,” he said, navigating his cab through Capitol Hill traffic.

He moved here from California because of a woman, but “It didn’t work out.” Still, he stayed.

He lives on the fringes of poverty, in the economically challenged part of Washington within spitting distance of the railroad tracks that transport businesspeople to New York or Boston a couple dozen times a day on the Acela Express.

The irony is not lost on Nigel. He understands, despite his economic struggles, that he literally lives along the Acela corridor, the famed connector of the highest concentration of the most elite people in America.

Nearly everyone getting on the Acela Express that day is either on their way up the ladder or, more than likely, already at the top; they are wealthy, successful, powerful, in the cross hairs or on the boards of what moves and shakes this country.

Yet, in Nigel’s neighborhood on the wrong side of North Capitol Street, prosperity and opportunity are not part of the narrative. He’s not envious, nor is he particularly interested in gentrification overtaking his neighborhood. “That’s just geography,” he said, explaining that it doesn’t solve the problem, just rearranges it.

Nigel voted for Barack Obama, twice: “It was a point of pride for me, as a black man, to cast my vote for the first black president. Wow! But it turned out he was no different than anyone else who held the office. Just another politician who could string together pretty words.”

No one has any idea what to do with the under-employed, high-school-educated people who once were able to carve out good, middle-class lives with their own hands.

In the Acela Express’ business class, your seat is big and comfortable; you can plug in your iPhone or laptop or use the club cafe to sip on a craft IPA or chardonnay.

Sit in first class and you get to enjoy hot towels, newspapers and beverages. Meals and drinks? Well, they are served to you at your seat.

The ride is a jarring anthropological experience — that is, if you bother to look up from your digital device.

Not because it is too fast, or the curves are too sharp; the jarring effect comes from the visual decay of our country swooshing by right before your eyes.

Outside, a different Acela corridor rolls by — one roiled by isolation, decay and societal changes, a world ghosted by technology, corrupt politicians and bad city planning.

Shuttered machine shops, refineries, steel mills and manufacturing plants near Trenton and Philadelphia slide past the window like a kaleidoscope of sorrow; scores of once-charming century-old houses are now covered in graffiti and dot areas in and around Baltimore, Newark and Wilmington, Del.

It used to be that the people who lived and worked along the Acela corridor were held in at least as much esteem as those in the urban bookends that connect them. They were the people who made the stuff that made this country great, mostly blue-collar, mostly union members, mostly middle-class.

They worked hard, they played hard. On Friday nights, when their shifts ended, they went to the neighborhood bars; on Sundays they prayed for their sins. And, in between, they coached their kids’ softball games or volunteered at the concession stands.

Politically, they mostly have been New Deal Democrats, believing that government was there to hold together the social fabric; they depended on it as much as the government depended on them.

Until, like Nigel, it didn’t anymore.

A lot of things have happened in this “other” Acela corridor, stripping it of prosperity and patriotism, once generated by the notion that people here were the engine that made this country roar. But mostly, it has been unrelenting automation that has eliminated middle-class jobs and lives.

A study by economists Pascual Restrepo of Boston University and Daron Acemoglu of MIT tried to quantify how worried we should be about robots — and it succeeded.

In short, it determined, every additional robot used in automation reduced employment in a given commuting area by three to six workers, and lowered wages by 0.25 to 0.5 percent. There are 1.5 million robots out there working in what is left of industrial America, and that number is projected to double in less than 10 years.

For Nigel, automation ultimately will kill the best income he earns as a cabdriver, since driverless-vehicle technology is fast becoming more of a reality. Lawrence Katz, a labor economist at Harvard, estimates that automated cars will impact the 5 million people nationwide who make their living by driving Uber, Lyft, taxis, buses, vans, trucks and delivery vehicles.

Katz points out that most of these drivers are people like Nigel — a man without a college degree — who’ve already been hit by the loss of 5 million manufacturing jobs since 2000.

Peering out the window of the Acela Express, the sadness of this other world speeds by like a faded collage of past lives, hopelessly waiting to be brought back to life.

President Trump, like him or not, wasn’t wrong when he said there was “carnage” in the country right now. Ironically, a lot of that carnage is located on this corridor, connecting eight of the 10 wealthiest counties in our nation.

The hard truth is that no one has any idea what to do with the under-employed, high school-educated people who once were able to carve out good, middle-class lives with their own hands, as long as they were willing to work.

But somebody had better figure it out soon: With nearly 70 percent of Americans lacking college degrees, this corridor will eventually crack, just like the dislocated voters of the Rust Belt.