We often forget that the American pattern of suburban development is an experiment, one that has never been tried anywhere before. We assume it is the natural order because it is what we see all around us. But our own history — let alone a tour of other parts of the world — reveals a different reality. Across cultures, over thousands of years, people have traditionally built places scaled to the individual. It is only the last two generations that we have scaled places to the automobile. The underlying financing mechanisms of the suburban era — our post-World War II pattern of development — operates like a classic Ponzi scheme, with ever-increasing rates of growth necessary to sustain long-term liabilities.
From Grist: http://www.grist.org/sprawl/2011-06-22-the-american-suburbs-are-a-giant-ponzi-scheme