WILLISTON, N.D.

Inside a trailer that has become their makeshift classroom, Kim Roth gathers her second-graders in a semicircle to gently break the bad news.

She won't be back next year to Round Prairie Elementary, their school on a treeless mound near the North Dakota-Montana border.

Roth, 41, has lived and worked in Williston nearly all her life. Now she's reluctantly moving to her in-laws' family farm northeast of Minot — far from all the new drilling rigs and oil truck traffic, far from the leering advances of rough-hewed men who have flocked to the flourishing oil fields, and far from her only grandchild, 2-year-old Emma.

With wide eyes, the children in her class ask: Why?

"Well," Roth sighs, "our town has changed."

As North Dakota erupts into one of the world's richest oil plays, there's a grimmer side to all the black gold: Locals who have long called these windy plains home are fleeing.

"The kids who live here, they kind of understand," Roth said. "They say, 'My dad said, 'We wish we could move, but we have our big farm.' "

Across the Missouri River, more than 300 miles east, Jim and Norma Stenslie share a similar story as they sit down to dinner.

The retired pastor and his wife have just finished moving a lifetime of belongings from the heart of the oil boom to their new stucco bungalow in the quiet town of Napoleon, population 766, south of Bismarck. They pause to say grace, asking God to bless their friends and family back home under the shadows of oil rigs.

Jim preached for decades in several steepled churches in western North Dakota. Norma taught piano and played organ in one of those Lutheran churches near Ross. Now in their late-70s, the ­couple planned to wind down their days in the family cabin on the banks of Lake Sakakawea near New Town.

Fracking for oil interrupted those dreams.

"From our spot on the lake, we used to be able to see stars and northern lights," Norma says. "It was heaven. Now all we see is oil derricks and flares."

While thousands of workers and billions of dollars flow in with the oil, losing teachers and preachers comes with a price.

"It's people we can't afford to lose, like the postmistress and the lady who drives the ambulance," said Marilyn Hudson, 77, from her kitchen in ­Parshall, on the eastern edge of the oil fields.

"It's people like the Stenslies, the good solid citizens who volunteer at the senior center, the folks who really contribute so much to the community," she said. "The people coming in are not stepping up to help out. They are not the same caliber of people as the residents who were here and became part of the land, part of the community and part of everything."

'You just sense more sadness'

When the Stenslies wed 56 years ago, after meeting at Moorhead's Concordia College in the 1950s, it was a marriage of North Dakotans from opposite ends of the state. Jim grew up out west in Watford City, in what's become the vortex of oil activity. Norma comes from the "perfectly" flat farmland to the east.

"There was nothing wrong with it and I love it dearly," she says of her childhood home near Hope. "But, oh, to be able to walk those hills and see the scenery near our cabin — there were all kinds of wonders to behold; we couldn't wait to retire."

They compare the pain of uprooting themselves to the grief they felt when their ­parents died.

"We both wanted to get out of the oil country, out of the traffic, out of the dust and out of the pain of watching all of the degradation to the hills and the places we loved," Jim says.

As darkness falls outside the window of their new wooded corner lot, and silverware clinks against dinner plates, they talk of new government forecasts that at least double earlier projections of where this oil boom is heading.

Even with nearly 200 rigs drilling around the clock and 7,500 wells dug so far, energy industry insiders say they've only extracted one-fifth of the oil now available for the taking.

"If this goes on as long as they say — 20 years? — I just can't imagine what it's going to look like," Norma says.

She recalls how excited her neighbors were when the boom began.

"All of a sudden, they could buy a new tractor, new equipment, a new pickup. But after a while, visiting with people at church, you just sense more sadness than there used to be. They're wearing down."

"And there's more stress and strain," Jim says.

The couple feel almost guilty about moving away from their friends and neighbors.

"We feel bad for people who, because of their vocations — farming or ranching — can't leave like we did," Jim says.

Now, in their new town of Napoleon, where they don't know a soul, Jim can ride his bike again and folks seem friendly enough.

"Everybody waves to everybody the way it used to be by our cabin," he says. But even that changed in the oil rush. "Back there, you don't know if it's anybody you should wave to or not."

The seedy side of a boom

Bruce Coonfield zipped up his bulletproof vest, grabbed a blue Gatorade off his desk and a pistol from a locked drawer. It was time for another shift patrolling 2,000 square miles of Williams County as a sheriff's deputy.

On his way out, he gazed down through a window into a county jail where a couple of dozen prisoners in striped jump suits milled around a common room. The Williams County jail in Williston used to average about 20 inmates a night before the latest oil boom took off in 2008.

Now, the jail has more than 115 prisoners on an average night.

Coonfield's first call found him steering his oversized Ford pickup squad car to an RV park, where he consoled a guy who just got punched in the nose.

The next call sent him zooming east down Hwy. 2, past the three-bar town of Ray and into the Wanzek man camp, where workers live in a maze of trailers. Someone got shot there a few months earlier, so a private security officer in a cowboy hat manned a ­metal-fenced entry gate.

The guard, relaying a tip, said that a welder from Illinois living there had two guns, a rifle and a pistol, in violation of camp rules. Coonfield checked the guy's blood alcohol level, determining he was sober.

The welder was angry. He'd been fired, so Coonfield escorted him off the property, but allowed him to keep his guns. The Second Amendment trumped man-camp rules and the man drove into the darkness toward a Minot motel, guns in tow.

"It's a tenant-landlord dispute, no laws were broken," said Coonfield, who worked as a carpenter in the ­Brainerd, Minn., area until construction jobs dried up six years ago and his wife got pregnant.

He studied law enforcement and joined the migration to western North Dakota and its abundance of jobs. About one-third of his department is composed of Minnesota transplants and the overall number of deputies has tripled to 24 since the boom began.

At 28 with a new child, their fourth, living in a $1,000-a-month trailer, Coonfield was earning $47 an hour, working 6 p.m. to 6 a.m.

He cruised the streets of Ray and Wildrose before circling back to downtown Williston near the train depot — home to two strip clubs, ­Heartbreakers and Whispers.

"This street has gone to hell," he said.

Bar closing is always ­raucous on this block, where strippers rake in big money from the pockets of well-paid oil workers and sidewalk scuffles are routine.

Crime is rising fast. Rape cases jumped 41 percent in oil-producing counties in 2012, climbing from 34 to 48.

In Williams County, the number of calls serious enough to generate reports, meanwhile, soared nearly fourfold since 2008 to 1,028 last year. Vehicle crashes also quadrupled.

Jennifer Gaines doesn't need statistics to tell the story. The former prostitute, now part of emerging local efforts to curb sex trafficking, said she would check into a Williston motel two years ago and head to a bar across the alley.

"I'd put in an 'escort' ad on backpage.com and my phone would blow up — I couldn't handle all the calls," said Gaines, 44, who'd worked in the sex trade since she was 13 before turning her life around recently.

Working women ride the train or buses to the oil fields, where "you could get $300 or $400 a trick and make a couple grand a day," she said. Sometimes, her regular customers would fly her up. "They think they're entitled to sex because they're up there working, making big money and they're away from their families."

Back in his squad car, with roadside gas flares blazing out his window, Deputy Coonfield slipped in a call to his wife, wishing her good night, as he cruised down a dark highway.

Soon, though, Coonfield had seen enough. This fall he quit to join the police department in Ada, Minn., closer to home.

"As a cop, I saw stuff out here I wouldn't have seen at any other jurisdiction," he said. "But with a young family, it was no place to stay."

'It's just not the same'

Growing up, Kim Roth attended a white school house with a red roof. Her dad ran an oil well safety business back during North Dakota's last oil boom and bust in the 1980s. She remembers what went through her mind when she was 7 and the snow melted and the prairie started to green up in springtime.

She knew that next year she'd be in second grade and who her teacher would be. Kids back then could count on stability.

But Round Prairie is not the school of her youth. Roth joined three other departing teachers and the principal, leaving Round Prairie after the doors shuttered for summer break. Just two teachers remained at the school of 93 kids.

"I will miss the kids, and it will be hard on them," Roth said, on the playground during recess. "They won't know who their teachers are going to be."

One by one, they filed back into the classroom. A girl from Alabama who was afraid to go outside for recess because she had no winter coat. A boy from Wyoming who lives in a camper.

Micah's dad is a farmer up the road near Genora. Laney's family lives just down the road. Her dad works in the oil fields. So does Sierra's.

"Keaton says he never sees his dad," Roth said. "He drives a truck and I'm not saying he's a bad parent. But when they're not home, it reflects. We're seeing increased behavior problems."

She remembered a little boy in her class, whose family slept in a camper behind the Four Mile Bar at a busy crossroads 4 miles west of Williston. The sheriff came out and found the boy, barely dressed, playing in the parking lot. His parents were inside, drunk. When he asked why the kids weren't in school, Kim recalled: "The mom said, 'I didn't know there was school here.' "

He was three months behind when he arrived in her classroom. "With all the factors at home, and all the adjustments for these kids, we tend to find they are behind and they come in struggling."

And now she had to tell this band of young faces she was leaving town. She explained that she and her husband are building a new house on his old family farmstead three hours to the east, away from the oil.

It was an agonizing decision.

When she married an agricultural chemical salesman named Lyle 13 years ago, she vowed to never leave Williston. Born in Montana, she moved to Williston with her family when she was 5.

"Everything was clean. You knew most of the people. Your kids could play outside without having to watch them. You didn't worry about everything as much."

She used to leave her car running when she went in to pay for gas. Then one day her son's iPod was ripped off from the car. She started locking up.

She used to walk around the school track near her home every morning for exercise. Not anymore, since another schoolteacher in her early 40s, Sherry Arnold, was kidnapped while jogging earlier this year in eastern Montana. Her body was found buried in Williston nearly three months later. Two drifters from Colorado were arrested after returning the shovel to the Wal-Mart in Williston.

Her own stops at Wal-Mart to pick up a few groceries had become a tense ordeal.

On a recent trip, an oil worker from Texas pinned her cart in the cracker aisle.

He asked for her name and whether she had a car.

"I kind of humored him because I was scared," she said. Then he wanted her number and to know if she were married. "I said, 'Yes.' He didn't seemed very concerned. It's just kind of yucky like that."

Williston, the carefree town of her youth, had become a place where "now you don't hardly want to make eye contact with some people, afraid what they'll assume."

Earlier this year, Lyle and Kim began talking more and more about moving away.

During one late-night chat, he brought up moving to the family farm near Granville. "We could build a nice house with a peaked roof,' " he said.

Finally, she nodded. "We need some peace, and we need to get out of this rat race."

That meant leaving behind 2-year-old Emma, her only grandchild, whose daily visits will now become occasional three-hour treks.

"That will be the hardest part for us to leave," she said. "The hardest."

They sold their house here for $250,000 — double what they paid — to a wealthy farmer her husband knew from his ag business.

"He's going to flip it and it will probably sell before we move out," she said, shrugging.

As the moving truck loaded up a few months ago, Kim fingered her mother's wedding ring diamond. She's worn it on a necklace since her mother gave it to her as a gift following her graduation from Minot State.

"I was raised here my entire life. My parents were both raised here. It will be sad, but a lot of my friends have already left, and it's not the same town. It's just not the same."

Curt Brown • 612-673-4767