Shellie Saffel walks the family dog in her South Riding, Va., neighborhood. The suburban ideal of big house, big lawn and big vehicle is threatened by gas prices.

The Washington Post / JAHI CHIKWENDIU

WASHINGTON — That 1958 brick rambler inside the Beltway is suddenly looking a lot better to Dawn and Jeff Schaefer, who are buying their first house in Northern Virginia.

Not too long ago, they were looking farther out — for a newer house, a bigger yard and all the amenities. But no more. “You get less house and property for the same price, but we’re willing to make that sacrifice to save on gas prices and commuting costs,” Dawn Schaefer said.

Cheap oil, which helped push the American Dream away from the city center, isn’t so cheap anymore. As more and more families reconsider their dreams, land-use experts are beginning to ask whether $4-a-gallon gas is enough to change the way Americans have thought for half a century about where they live.

“We’ve passed that tipping point,” U.S. Transportation Secretary Mary Peters said.

Since the end of World War II, government policy has funded and encouraged the suburban lifestyle, subsidizing highways while starving mass transit and keeping gas taxes much lower than in some other countries.

Americans couldn’t wait to trade in the cramped city apartments of the Kramdens and Ricardos for the lush lawns of the Bradys. Local land-use policies kept housing densities low, pushing development to the periphery of metropolitan regions and forcing families who wanted their dream house to accept long commutes and a lack of any real transportation choices other than getting behind the wheel.

Even the way the government pays for roads and transit depends on gas taxes, which is effective only if Americans keep driving.

“There is a whole confluence of government policies — tax, spending, regulatory and administrative — that have subsidized sprawl,” said Bruce Katz, director of the Metropolitan Policy Program at the Brookings Institution. A gallon of gasoline costs more than $8 in Britain, Germany, France and Belgium, according to the U.S. Department of Energy. Much of the price difference is due to higher taxes.

Federal spending is about 4 to 1 in favor of highways over transit. Today, more than 99 percent of the trips taken by U.S. residents are in cars or some other non-transit vehicle, largely as a result of decades of such unbalanced spending.

The policies — building so many highways and building so many houses near those highways — have had a direct bearing on how and where people live and work. More Americans, 52 percent, live in the suburbs than anywhere else. The suburban growth rate exceeded 90 percent in the past decade.

But there’s been a radical shift in recent months. Americans drove 9.6 billion fewer highway miles in May than a year earlier. In some cities, mass transit ridership is setting records. Last year, transit trips nationwide topped 10.3 billion, a 50-year high.

The Brookings Institution says transportation costs are now second only to housing as a percentage of the household budget, with food a distant third.

The people are leading the revolution, but land-use experts wonder whether a government policy so etched into the American fabric will follow.

“When people bought homes, they punched the numbers and said can we afford the mortgage payment and taxes,” Katz said. “This new paradigm is going to have families being more deliberate about the cost of transportation spending and energy costs. That’s a new phenomenon in the United States. That will be the change that will change development patterns.”

Katz and others said high fuel prices will increase demand for transit-oriented development, where homes, townhouses and office buildings cluster around transit hubs that link jobs with population centers.

That is the model that Tom Darden, chief executive of Cherokee Investment Partners, is betting on. His Raleigh, N.C.-based firm snaps up urban land, often used industrial sites, near transit stations and transforms it into housing.

He said the days of building giant houses on former soybean fields on the outer fringes of metropolitan areas are over.

“What were pluses of that lifestyle are now liabilities: a big SUV, a big home to heat, the energy needed to mow the lawn,” he said.

He said his urban properties in Charlotte, Raleigh, N.C., Montreal and Denver are doing well, while exurbs like those in California’s Central Valley are “turning into ghost towns.”

“And we’re only at the shallow end of the pool,” Darden said.

In Montreal, Cherokee bought a former General Motors plant in 2004 and is creating a mixed-use development that will include 1,200 residential units on a transit line stop. In Denver, Darden’s company is doing something similar with an abandoned rubber plant.

“Longer term, rising fuel prices produces a positive effect: people living closer-in and in smaller homes and close to transit,” Darden said.

David Ellis, a researcher with the Texas Transportation Institute, said the desire for such development is driven by demographics and public demand, not government fiat.

“Government can facilitate only when there is a demand,” Ellis said. “If government does something against the market, it is going to fail.”

But density remains a tough sell to those who want a house with some land and who don’t live or work where the trains go.

“It is fatuous to believe that because fuel costs $4 a gallon today that we will all decide to live in apartment houses,” said Alan E. Pisarski, author of Commuting in America and a leading national expert on driving habits and trends.

“The economic reality is that people get forced to the edge of metropolitan areas,” Pisarski said, adding that the decades-long outward march made economic sense in the days of lower home prices and cheaper commuting costs.

Even at these high gasoline prices, he doesn’t foresee a major shift in those trends.

“The only answer over time is that the jobs come to them,” he said, referring to employers moving out to be closer to their exurban workers.

The debate over density is not just limited to the East and West coasts.

Mayor Randy Pye, mayor of Centennial, Colo., a suburb of Denver, has been called a socialist by fellow Republicans for his pro-density and pro-transit views. He was a supporter of the Denver area’s new light-rail system, a system built largely without federal funds.

Pye said he doesn’t see a way out of high gas prices and our collective national traffic jam that doesn’t involve higher-density development and mass transit.

“We hate density; we hate sprawl,” he said. “But we can’t continue doing what we’re doing.”