WILLISTON, N.D. — Christina Knapp and a friend were drinking shots at a bar in a nearby town several weeks ago when a table of about five men called them over and made an offer.

They would pay the women $3,000 to strip naked and serve them beer at their house while they watched mixed-martial arts fights on television. Knapp, 22, declined, but the men kept raising the offer, reaching $7,000.

“I said I make more money doing my job than degrading myself to do that,” said Knapp, a tattoo artist with dark streaks in her light brown hair, a bird tattoo on her chest and piercings above her lip and left cheekbone.

The rich shale oil formation deep below the rolling pastures here has attracted droves of young men to work the labor-intensive jobs that get the wells flowing and often generate six-figure salaries. What the oil boom has not brought, however, are enough single women to provide balance.

At work, at housing camps and in bars and restaurants, men have been left to mingle with their own. High heels and skirts are as rare around here as veggie burgers. Some men liken the environment to the military or prison.

“It’s bad, dude,” said Jon Kenworthy, 22, who moved to Williston from Indiana in early December. “I was talking to my buddy here. I told him I was going to import from Indiana because there’s nothing here.”

This has complicated life for women in the region as well.

Many said they felt unsafe. Several said they could not even shop at the local Wal-Mart without men following them through the store. Girls night out usually becomes an exercise in fending off obnoxious, overzealous suitors who often flaunt their newfound wealth.

“So many people look at you like you’re a piece of meat,” said Megan Dye, 28, a nearly lifelong Williston resident. “It’s disgusting. It’s gross.”

Prosecutors and the police note an increase in crimes against women, including domestic and sexual assaults.

“There are people arriving in North Dakota every day from other places around the country who do not respect the people or laws of North Dakota,” said Ariston Johnson, the deputy state’s attorney in neighboring McKenzie County, in an email.

Over the past six years, North Dakota has shot from the middle of the pack to become the state with the third highest ratio of single young men to single young women in the country. In 2011, nearly 58 percent of North Dakota’s unmarried 18-to-34-year-olds were men, according to census data. That disparity was even starker in the three counties where the oil boom is heaviest — there were more than 1.6 young single men for every young single woman.

And most people around here say the gap is considerably larger. Census data mostly captures permanent residents. Most of the men who come here to work maintain their primary residences elsewhere and split time between the oil fields and their homes. And women note that many of the men who approached them are married.

Some women have banked on the female shortage. Williston’s two strip clubs attract dancers from around the country. Prostitutes from out of state troll the bars.

Natasha, 31, an escort and stripper from Las Vegas, is currently on her second stint here after hearing how much money strippers made in Williston on a CNN report last year. Business in her industry is much better here than in the rest of the country, she said. She makes at least $500 a night, but more often she exceeds $1,000.

“We make a lot of money because there’s a lot of lonely guys,” she said.

But some men have forced themselves on women.

Jessica Brightbill, a single 24-year-old who moved here from Grand Rapids, Mich., a year and a half ago, said she was walking to work at 3:30 in the afternoon when a car with two men suddenly pulled up behind her. One hopped out and grabbed her by her arms and began dragging her. She let her body go limp so she would be harder to drag. Eventually, a man in a truck pulled up and began yelling at the men and she got away, she said. The episode left her rattled.

Going out alone is now out of the question, and the friend she moved here with no longer has much time to spend with her because she has since found a boyfriend and had a baby. Brightbill said she has difficulty finding other young single women with the freedom to hang out. And, she said, finding good men does not come easy.

“It’s just people trying to have sex,” she said.

But some women have taken aggressive steps to protect themselves.

At the urging of her family, Barbara Coughlin, 31, who recently moved to Williston after her 11-year marriage ended, is now getting her concealed weapons permit so she can carry a Taser. Coughlin, who wore silver glitter around her eyes at work as a waitress on a recent day, said her mother and stepfather, who live here, advised her to stop wearing the skirts and heels she cherishes, so she does not stand out like “a flower in the desert,” as her stepfather put it. Her family hardly lets her go out on her own — not even for walks down the gravel road at the housing camp where they live.

“Will I stay for very long? Probably not,” she said. “To me, there’s no money in the world worth not even being able to take a walk.”