Unemployment is a national problem in the United States, but you wouldn't know that if you traveled through North Dakota.

Suddenly, people are moving to the Peace Garden State, where an oil boom has immunized residents from the most severe recession in decades. Wages are up, and work is plentiful.

The state's unemployment rate recently hovered a little above 3%, and "Help Wanted" signs litter the landscape of cities such as Williston in the way "For Sale" signs populate the streets of Las Vegas.

"It's a zoo," said Terry Ayers, who came to town from Spokane, Wash., slept in his truck and found a job within hours of arrival, tripling his salary. "It's crazy what's going on out here."

Billions of dollars are coming into the state and thousands of people are following -- all because millions of barrels of oil are flowing out.

The result: An old-fashioned oil boom.

There's little available housing in parts of North Dakota, so newcomers sleep in truck stops and parking lots of Wal-Mart stores. Developers are building hundreds of houses and thousands of apartment units.

The McDonald's in Williston is one of the busiest in the country, and it needs to pay $15 an hour just to attract employees.

And then there are the trucks -- thousands of them -- on the state's roads. One left turn in Williston gets so backed up with truck traffic that it can take hours to get through the intersection.

Managing growth

"If you're not making money now, there's a major problem," said Williston Mayor Ward Koeser, who is overwhelmed with managing the city's growth. Among the problems Koeser is grappling with are sewage treatment, building permits and an exponential increase in traffic violations.

As for the oil itself, it comes from the Bakken rock formation, which spans 14,000 square miles in North Dakota, Montana and Canada. The U.S. Geological Survey says there are at least 4 billion barrels of recoverable oil in the Bakken, but other estimates indicate that it could be four to five times that.

"Clearly, it is the largest oil field we've found in North America in the last 40 years," said Bud Brigham, the founder and chief executive of Brigham Exploration (BEXP, news), which has staked the company's future on the Bakken oil business. "If it's more than 15 billion barrels, it may be the biggest oil field found in America ever."

Fortunes tied to 'fracking'

The Bakken has been a known source of oil for decades, but only in recent years has it become feasible to profitably get the oil out of the ground. There are two reasons for this: oil prices and drilling technology.

Oil companies, including Brigham, Continental Resources (CLR, news), Hess (HES, news) and EOG Resources (EOG, news), drill two miles down and two miles horizontally. Then, they use hydraulic fracturing, or "fracking," to create space for oil to flow out of the rock -- hundreds of thousands of barrels a day, literally one drop at a time.

"In a couple of years, the Williston Basin (where the Bakken is located) will surpass the oil production out of Prudhoe Bay, Alaska," said Rick Muncrief, senior vice president at Continental.

Of course, that's as long as prices remain relatively high and fracking is allowed to continue.

"Where we are today, we can generate really solid returns at $65 to $70 a barrel," said Bud Brigham.