But despite the pleasant surface, sprawl and traffic continue to push inward. As Nassau County executive Tom Suozzi has said, the old model of suburbia -- one of single-family houses set apart from one another, which began with Levittown 60 years ago -- is no longer sustainable.

Nassau County’s population is smaller now than it was in 1970, and the town has run out of developable land. Taxes are high, and young people are leaving. Suozzi recently prepared a campaign to develop Levittown America’s first “green” suburb -- but residents told me it's gone nowhere so far.

Mullan believes the economics of suburban living will eventually force things to change, although he anticipates resistance.

"One idea about suburbia is a house on a big piece of property with space and trees. We don’t want to think about blacktop and cars. We don’t want to think about change," he said. “My American dream was a house, and a yard, and a family -- a homestead.”

He asked my age; I told him I was 26. “I believe my American dream is not your American dream. The idea that you’re not a success unless you own a home -- your generation or the next is not going to hear that. It’s not [going to be] what defines a person.”

As a result, home ownership -- a devoutly held ideal that Levittown helped create -- will lose its value. Owning grass, as Mullan joked, won’t be the end-all of human existence.

At first mild-mannered, Mullan grew passionate talking about how the suburbs should adapt. As sociologists and city planners have argued, Mullan believes that zoning needs to change to reflect that commercial and residential properties may have to share the same street. People will need to draw closer together, not further apart.

After nearly 80 years and 200,000 homes, Levitt & Sons filed for bankruptcy in late 2007 -- the result of bad bets on luxury homes in southern Florida. It's a sad, ironic twist on the American dream: The builders that helped to create it were ultimately sunk by its pursuit.