They’re on the road, uprooted but resilient, migrating with the seasons, following work or just avoiding the bitter cold or murderous heat. But don’t call them “homeless.”

“I’m not homeless,” “Nomadland” van-dweller Fern, played by Oscar winner Frances McDormand, explains to the child of an old friend. “I’m just houseless.”

Filmmaker Chloé Zhao makes Fern both our tour guide and our introduction to this rootless subculture in “Nomadland,” an elegiac character study and somber docudrama about Americans living on the edge.

These are lives in the open spaces, touched by the romance of the open road. But it’s an existence with little margin for error, a nationwide population who are the new Okies in a modern “Grapes of Wrath.”

We meet Fern driving her aged panel van from her hometown of Empire, Nevada, a one-factory town that lost its factory and its zip code within months of each other. Widowed and alone, she migrates to the first of a string of new “homes” and temporary, seasonal jobs — an Amazon packing and distribution center.

Over the course of “Nomadland” Fern will clean toilets at Badlands National Park and cook at famed tourist attraction Wall Drugs in South Dakota, shovel beets in Nebraska, and learn about this lifestyle from its elders — people like the 70something Swankie (Charlene Swankie) and camper-nomad guru Bob Bell, both playing versions of themselves.

Fern makes friends, and friends like Linda May look out for each other, point her to places where there’s work. But have a flat that you can’t fix on your own in a place with no cell service, and Swankie will give you an earful.

“You can DIE out here.”

We have hints of what’s put Fern in this state of affairs, and Zhao leaves details out, focusing on the interior journey. Thus, an employment counselor who suggests Fern “consider early retirement” may mean well. But Social Security, social service help and healthcare are not in the picture, as indeed they aren’t for millions of Americans.

Bell, creator of Youtube tutorials on how to manage this life, preaches to the newly-converted at an Arizona gathering of nomads whimsically named the RTR — “Rubber Tramp Rendezvous.” They’re escaping “the tyranny of the dollar” and “the yoke of capitalism.”

Zhao, who first gained fame with her somberly reflective rodeo drama “The Rider,” romanticizes this lifestyle without sentimentalizing it.

A fellow nomad in an RV park has a stroke and his dog needs a new owner and home. We want Fern to take it. She won’t. Sad-eyed and somewhat clumsy Dave, played by David Strathairn, shyly makes his interest in Fern’s company known. Does he have a prayer?

It’s implied Fern has to fret — like everybody else who lives like this — where she’s allowed to park for the night or camp on the cheap. By emphasizing (probably exaggerating) the friendly, communal nature of this existence, Zhao leaves most of the dangers involved out. But statistically, the people who take to the roads this way are almost all broke, almost entirely white, and that’s the world Zhao shows us.

Solitary Fern is choosy about who she’ll get arms-length-close to, determined to be self-sufficient, taking stock of just how hard that is when she hits her sister (Melissa Smith) up for cash. But she’s also totally present in her free time, taking nature walks in National Parks, visiting gigantic concrete dinosaurs, dropping in on a stargazing excursion and skinny dipping solo in a rocky western river.

McDormand lets us see a smile here and there. But the odd outgoing moment doesn’t hide Fern’s thousand-yard stare, the sadness we sense and the eyes-down focus on the next step, next fill-up, next repair, next parking lot, next job, next meal and next public restroom.

No guru enthusiast or colorful TV feature story about the “romance” of it all can hide that this is a very limited, depressing way to live. And one of the finest actresses of her generation makes us sense that and the pondering Fern must do, weighing this rotten poker hand life has dealt her and also which forks in the road that she has taken brought her here.

“Nomadland” is a film of stark beauty and grim, grey reality.

As with “The Rider,” Zhao is sparing with her dialogue and lets images and acting do most of the storytelling. She rewards the viewer who can guess how Fern is able to shower off this day’s work at the beet processing refinery and who picks up on Dave’s shortcomings — that senior style out-of-date cell phone where he keeps the PIN written on tape on the screen.

One can’t help but see this as a depiction of a lifestyle would have been impossible to romanticize in 2020 — with even many of the menial jobs Fern takes vanishing, and staggering competition for the few such gigs left. The “freedom” of “Nomadland” looks a lot less alluring in that light.

But marrying this “Grapes of Wrath” saga to a “journey of self-discovery” narrative in a blend of restlessness and dogged, “no whining” desperation makes “Nomadland” an instant indie classic and one of the best films of 2020.

MPA Rating: R for some full nudity.

Cast: Frances McDormand, David Strathairn, Melissa Smith, Linda May, Bob Wells and Charlene Swankie

Credits: Written and directed by Chloé Zhao, based on the book by journalist Jessica Bruder. A Searchlight release.

Running time: 1:47