– Clanking and chuffing, belching black smoke and hissing white steam, they crawl over the rolling hills like an army of giant Erector Set toys.

Attended by a swarm of cheerful, greasy farmhands, these behemoths were the mechanical marvels of their day, relieving Midwestern farmers of the backbreaking drudgery of heavy labor: plowing fields, sawing wood, threshing wheat, grinding feed.

And as they have each year since 1954, scores of antique steam traction engines (don’t call them tractors!) are gathered on the cusp of the Red River Valley over Labor Day weekend and put through their paces before an admiring audience in this western Minnesota hamlet.

Rollag is a dot on the map, a speck on the prairie, a wide spot in the road with a country Lutheran church on either side. It has no local government and no official population. It’s the kind of place where everyone within 20 miles knows everyone else’s grandparents.

Yet for one long weekend a year, it’s the hottest spot between the Twin Cities and Winnipeg.

While many Minnesotans head south for the final weekend of the State Fair, some 70,000 enthusiasts from Minnesota, the Dakotas and other Midwestern locales make the trek to Rollag for the annual Western Minnesota Steam Threshers Reunion. This is the real Machinery Hill, a gathering with a distinctly agricultural flavor.

Old men wearing feed hats mix with middle-aged bikers in Sturgis gear, while neatly dressed Mennonite children wander hand in hand. It’s a place where bib overalls are a badge of honor, the apparel of most of the 2,000-plus volunteers who make the place go. But talk to just about anyone, and they live on a farm, grew up on a farm or had farming somewhere in the family tree.

The Rollag grounds cover more than 260 acres and include a “sandbox” where giant steam shovels gulp bucketfuls of earth, a re-creation of a prairie town and a smattering of church dining halls serving family-style meals. Along with the traction engines, there are more than 600 stationary steam engines housed in permanent buildings, all built and maintained by volunteers.

During the four-day reunion, the gathering announces itself with a giant black pall, visible from 10 miles, hovering over the hillside like an angry thunderhead. The grounds are suffused with smoke: wood, coal, oil and kerosene. It’s not an asthma-friendly atmosphere.

But for those who return there every year, Rollag is magical.

“It’s God’s country,” said Peggy Halverson, who grew up in Rollag and lives in nearby Downer, Minn. “There’s some heart and soul. You see a 75-year-old person, normally they’re hobbling. They come here and they’re reliving their youth.”

The threshers reunion (everyone just calls it “Rollag”) is among the largest such gatherings in North America and one of the largest in the world. It’s a homecoming of sorts for the machines, many of which were made in the Midwest, the manufacturing center for farm equipment in the latter part of the 19th century and into the 20th.

J.I. Case from Wisconsin, Rumely from Indiana and Avery from Illinois were all leading names. And then there was the Minneapolis Threshing Machine Co., which built steam engines at its shop in Hopkins.

Rollag is crawling with rare Minneapolis Threshing engines, such as the 1916 model operated by Nicole Wallace and Jen Roth, the Ladies of Steam. Wallace, an agricultural engineer from Frazee, Minn., and Roth, a clinical psychologist from Sartell, are on a mission to get women involved in the steam hobby. (It seems to be working. Their Facebook page has more than 7,000 followers from 60 countries.)

Dressed in blue overalls, engineer hats and grimy leather gloves, their cheeks smudged with grease, they look like Hollywood’s ideal of what a lady steam engineer would look like. But they’re the real thing — duly licensed, they’ve operated engines at shows all over the world, returning recently from a big exhibition in Great Britain.

Running on relationships

Back in the day, the harvest was a community event. The big steam engines would rumble from farm to farm for threshing, and everybody pitched in, with the men running the machinery and the women serving up huge home-cooked meals to the crews.

Rollag captures that feeling of community. Plunk down $8 at one of the Lutheran church dining halls and dish up your own breakfast from heaping platters of eggs, bacon, potatoes, sausage and pancakes. Nobody is watching to see how high you pile your plate. (Or, if they are, they won’t say anything to you about it.)

That family atmosphere is as much a part of the gathering as wood smoke, said Wallace, who grew up on a dairy farm near Detroit Lakes.

“The big thing with running steam engines is the relationships,” she said, “being able to engage in the history of agriculture in our area and teach people about farming.”

Wallace and Roth teach an introductory steam school for women at Rollag; this year’s session drew more than 50 attendees.

Fred Thomson is a city dweller with farming in his blood. Thomson, who grew up in Edina and lives near Delano, spent all his youthful summers working on his grandparents’ farm in Whitman, N.D.

“My old farmer cousins from North Dakota would go [to Rollag] every Labor Day weekend. They always told me, ‘You’ve got to go,’ ” he said. Finally, Thomson made the trip with his 5-year-old son, Cooper, and they were hooked.

Thomson has been running a steam engine for the past eight years. And Cooper, now 17, is right there with him. This year, the pair crewed a Rumely pulling a five-blade gang plow in the big plowing demonstration.

“It was exciting,” Thomson said. “We broke stuff and we fixed it and we got all dirty and hot and nervous and calm.

“We spend the whole week there and we work our asses off, and then sit around the campfire and drink a few beers, and then get up the next morning and do it again.”

A sensory experience

Wander through the woods on the north side of the grounds and you’ll find a small city with activity everywhere.

There’s a merry-go-round with a pipe organ, a foundry and several sawmills. Cream separators, washing machines and feed grinders. You can buy a sack of Swany White flour, milled on-site. A locomotive circles the grounds, taking visitors on a leisurely 15-minute ride. And it’s all powered by steam.

Some of the steam engines are so huge that they have stairs attached to them, such as the giant 85-ton Corliss engine that once powered the Pabst brewery in Milwaukee. Others are miniatures, lovingly built by the same kind of hobbyists who build ships in bottles.

Rollag is a sensory experience. Sounds and smells are everywhere: the tap and ring of a hammer on an anvil; clanking iron chains and slapping leather belts; the whine of saws and the roar of engines; the scent of freshly cut wood and freshly squeezed cider.

These machines display their workings, unlike modern digital boxes that hold mysteries only experts can fathom. The world of steam is straightforward: Wood heats water; water makes steam. A gear turns a wheel; a wheel turns a belt.

The whole place has been shepherded for generations by the Nelson family, which once farmed the land where the threshers reunion is held. The reunion really took hold after World War II, when the Nelsons pulled their old machinery out of the barn and got all the cousins together to celebrate the return of their solders from the war. By 1954, it had grown from a family event into the beginnings of what it is today.

“It’s not just a farm show,” said Eric Nelson, the grandson of founder Norman Nelson. “We are a living museum of history from the turn of the century.”

The show continues to grow, he said. Every Father’s Day weekend, the “University of Rollag” teaches beginners the care and feeding of the massive steam machines. The 2019 session, still nine months away, is fully booked with 75 students.

Rollag has some of the rarest engines still in existence; some of them would sell for close to half a million dollars. But they’re for go, not for show. None of them sits behind velvet ropes — they’re busy working.

Three generations of the Hein family were there over Labor Day, a trip they make each year.

“There’s stuff for us, for the kids and for Grandma and Grandpa,” said Ashley Hein, who lives in Worthington. “We used to go to the State Fair, but this is very kid-friendly and safe.”

And there are other, more pragmatic, reasons to go to Rollag.

“I totally married into this,” Christina Hein said with a laugh. “And now I’ve been told it’s a tradition.”