In the Twin Cities suburb of Columbia Heights, police officers say they know about North Dakota. Their detective colleagues at the Anoka County sheriff’s office know that when a local girl goes missing to check North Dakota’s Backpage ads.

Girls on the street talk about the oilfield, Columbia Heights police officer Maggie Titus said as she participated recently on a Twin Cities panel discussing sex trafficking. Some have visited the Oil Patch, she said, and men working legitimate jobs there come home to Minnesota and talk about how visible the sex trade is.

“It’s unfortunately a free-for-all up there,” Titus said. “There’s no wives.”

Women who post on Backpage.com say pimps are among their callers, trying to recruit them.

Kimberly Lovett, who marched in a rally against sex trafficking in St. Paul last fall, said she left that life behind about a year ago. “I ain’t for sale no more,” she said. “I’m just done with it.”

Cities between Minneapolis-St. Paul and the Bakken also report seeing an increase in sex trafficking.

Willie Navy, arrested on sex trafficking charges in November in Moorhead, Minn., was on his way to Williston, N.D., and had promised a woman she’d make $500 to $1,000 an hour there, according to court records.

“Unfortunately, we’re seeing a lot of our metro girls being brought out to the oilfields,” Anoka County sheriff’s Detective Thomas Strusinski said in an interview.

Lovett, of the Twin Cities, was in prostitution and exotic dancing for 26 years, spending the past decade traveling through Minot, Williston, Watford City, Fargo in North Dakota and cities in South Dakota.

While in North Dakota’s Oil Patch, she said she’d earn $1,000 on a bad night.

While Lovett says she didn’t have a pimp, she said she knew of women and girls who were trafficked to the area.

“There are some pimps that moved in and bought some houses up there and are keeping the girls up there,” she said. “Because the money is unlimited.”