CHICAGO (Reuters) - Traci and Brian Bruckner between them commute 800 miles a week to and from their respective jobs -- his 30 miles away from their home in one direction, hers 50 miles away in another.

Gas station owner Osama Elkhawad holds on to the money given to him by a customer to prepay for fuel at his station in Arlington, Virginia, June 11, 2008. REUTERS/Jim Young

With gas prices up 25 percent up since they moved to Wayne, Nebraska, just two years ago, Traci says they have been forced to cut back everywhere and postpone replacing the car Brian relies on to get to work.

“It has 200,000 miles on it so we need to get a new one,” she said. “But we just can’t afford to.”

The spike in fuel prices pinching U.S. consumers is creating special challenges in the country’s rural heartland, where residents typically earn less than their urban counterparts and travel longer distances -- often in older, less efficient vehicles -- to get to work.

Experts worry that if the surge continues -- while prices have eased over the past month, the cost of an average gallon is still up 30 percent over the past year and double what it cost four years ago -- it may threaten a three-decade-long population rebound that helped revitalize the country’s rural core.

For much of the 20th century, most rural U.S. counties saw their population shrink as mechanization of agriculture eliminated jobs and pushed residents toward the big cities.

But that began to shift in the mid-1970s, as Americans began to flock back into rural areas.

Today, an estimated 50 million Americans -- about 17 percent of the population -- reside in the countryside. Only one-fifth of those live in so-called exurban areas -- on the fringes of cities. The rest live in places like Tipton, Iowa, the town of 3,200 where Bob Bird moved a decade ago to enjoy the simplicity -- and affordability -- of rural life.

“It’s a great place to live,” said Bird, who drives 80 miles a day to his job as a roofer in Davenport. “But you can’t work here.”

Like Bird, many Tipton residents support themselves by driving to jobs in Davenport, as well as cities like Iowa City and Cedar Rapids.

“When I got here, 10 years ago, gas was $1 a gallon,” said Bird. “It wasn’t even a factor. I just enjoyed living in the country and so we just kind of took it in stride. But now it’s a little crazy.”

Experts say a number of factors contributed to the urban exodus and the rural renaissance, including frustration with housing costs, schools, crime and congestion associated with cities.

But cheap gas prices also played a role, making it possible for Americans to enjoy the best of both worlds: the peace, quiet and perceived affordability of rural living while still getting paid in big city dollars.

“Commutes of 35, 40 miles each way are not uncommon out here in the country,” said Chuck Hassebrook, the executive director of the Center for Rural Affairs, a policy analysis and advocacy group focused on rural life in the upper Midwest and Great Plains. “So higher gas prices hurt.”

Higher gas prices also make rural life a lot less idyllic, and less attractive to the urban refugees they rely on to sustain their populations.

In rural areas on the fringe of urban areas, the so-called exurbs where an estimated 10.8 million people lived in 2000, according to the Census, access to commuter rail networks or car pools gives residents alternatives.

But out in the real country, where another 40 million people live, there are few alternatives to the automobile. Telecommuting -- working an office job from home -- hasn’t really taken root. As a result, the pain of higher fuel prices is magnified.

“There’s no car-pooling out here,” said Anna Marie Percuoco, a stay-at-home mom in Long Grove, Iowa, population 600, whose husband drives a pickup truck 30 miles a day to his job in the city of Davenport.

Kenneth Johnson, a sociologist at Loyola University in Chicago, said that if the rural renaissance ends because places like Long Grove and Tipton stop attracting new residents, the economic effects won’t be confined to the countryside.

“Energy cost acceleration cuts both ways,” said Johnson, whose research has focused on trends in small-town America, noting that the urban areas are dependent on the broad rural labor markets for their workers.

Experts say another key question is what effect high energy prices will have on the rural areas, like those around the Great Lakes, that have seen their populations rise as they have become popular places to vacation or build a second home.

Johnson said migration to those counties, particularly in the more remote parts of northern Michigan, northern Wisconsin and northern Minnesota, has already started to slow because of the U.S. housing slump, which has made financing a second home using equity in the first a lot harder.

“If energy prices begin to have an impact it could really slow growth,” he said.

Steve Grubbs, whose Davenport-based sign-making company employs a number of rural residents, said those workers are already feeling the pinch. “I have one guy who has switched to riding his motorcycle in every day to save on gas,” Grubbs said. “I don’t know what he’s going to do this winter.”

To help ease the pain, Grubbs has begun offering prepaid gas cards as a reward to employees. Interest in the cards has been significant, he said.

Bird, the Tipton resident who works in Davenport, isn’t ready to give up the rural lifestyle just yet. But he is in the market for a more fuel-efficient vehicle for his daily commute. Used, of course.