He passed a drug test and trained for two weeks in Denver before settling, in July, into his new home away from home: a 7-by-11-foot cubicle at a “man camp.” A sort of cross between a military barracks and a college dormitory, temporary man camps have sprung up in and around Williston to help house the influx of workers from around the country.

Mr. Ripka is one of thousands of men with similar stories. They have descended on Williston and its environs over the last two to three years, pulled by the magnet of jobs created by an oil boom with the potential to make the region one of the largest petroleum resources in the country, and pushed by the hope that a steady income can put their finances back on track after a grueling downturn. While the national unemployment rate is 8.3 percent, in North Dakota it is 3.2 percent — and it is 1 percent in Williams County, where Williston has grown from a population of 12,500 before the boom began in 2008 to an estimated 20,000 now…

Because of the fast pace of oil well development to tap the Bakken shale field, the men often are on call around the clock and are away from their families for extended periods. A typical schedule might be to work 15 days straight, followed by six days off to go home. Airfare out of Williston can be steep, though, so many workers drive or take an Amtrak train, which adds travel time that cuts into their visits. (Some companies occasionally offer to put family members up in local hotels for visits.)

But not everyone goes home. The men can earn extra money — $150 to $200 a day or more, depending on the job — by working their scheduled days off, so many do. That means, though, that they are away from home for five weeks at a stretch, or even longer.