Some participating suburbs were already pursuing aggressive emissions-control measures, even before signing the agreement. Northbrook, Ill., near Chicago, now buys credits for 4,500 megawatt-hours of electricity from wind farms, enough to offset all the power consumed by its water utility, saving an estimated 4.9 million pounds of carbon dioxide emissions a year, said John Novinson, the Northbrook village manager. Like many other suburbs, it has also changed its traffic signals to energy-efficient L.E.D. models, and has enforced no-idling rules for motorists  including police officers.

SO far, Mr. Novinson said, residents have found the efforts to be relatively painless.

“The wind energy is costing people five cents per thousand gallons of water,” Mr. Novinson said. “It’s a nominal increase in water bills, for which we received nothing but positive comments.”

More symbolically, Nassau County officials started the Green Levittown program in the landmark suburb that was carved out of a potato field on Long Island in 1947. The initiatives are intended to persuade residents to conduct a home energy audit (at a cost of $150). The county then offers discounts rebates, and low-interest loans to anyone who switches to energy-efficient light bulbs, solar power, bio-fuels and upgraded home insulation.

Children in many schools are also being encouraged to walk or bike to school through the federal program Safe Routes to School, which has helped build bike paths, train crossing guards, and improve roadway safety in towns and suburbs around the country. (The percentage of children who walk or ride bikes has plummeted from 50 percent in 1969 to 15 percent in 2001, according to federal studies.)

A pilot program started in Marin County, north of San Francisco, in 2000, where at the time, surveys showed that 21 percent of children at nine schools surveyed either walked or rode their bikes to school. Two years later, that number was 38 percent, said Deb Hubsmith, the national director of the program.

Despite the efforts of individuals and whole communities to reduce the carbon cost of suburban life, the broad trends in American life have been moving in the opposite direction for decades. The average single-family home nearly doubled in size from 1970 to 2005, to 2,434 square feet. Americans commuting to work by car travel farther as suburbs sprawl (an average 12.1 miles in 2001, up from 8.9 miles in 1983), in vehicles whose average fuel efficiency has improved little.