Though Mr. Boyle finds city life unappealing, it is now up for reconsideration.

“Living closer in, in a smaller space, where you don’t have that commute,” he said. “It’s definitely something we talk about. Before it was ‘we spend too much time driving.’ Now, it’s ‘we spend too much time and money driving.’ ”

Across the nation, the realization is taking hold that rising energy prices are less a momentary blip than a change with lasting consequences. The shift to costlier fuel is threatening to slow the decades-old migration away from cities, while exacerbating the housing downturn by diminishing the appeal of larger homes set far from urban jobs.

In Atlanta, Philadelphia, San Francisco and Minneapolis, homes beyond the urban core have been falling in value faster than those within, according to an analysis by Moody’s Economy.com.

In Denver, housing prices in the urban core rose steadily from 2003 until late last year compared with previous years, before dipping nearly 5 percent in the last three months of last year, according to Economy.com. But house prices in the suburbs began falling earlier, in the middle of 2006, and then accelerated, dropping by 7 percent during the last three months of the year from a year earlier.

Many factors have propelled the unraveling of American real estate, from the mortgage crisis to a staggering excess of home construction, making it hard to pinpoint the impact of any single force. But economists and real estate agents are growing convinced that the rising cost of energy is now a primary factor pushing home prices down in the suburbs, particularly in the outer rings.