Here's some of the story:
"In the past three decades, Chicago has undergone changes that are routinely described as gentrification, but are in fact more complicated and more profound than the process that term suggests. A better description would be 'demographic inversion.' Chicago is gradually coming to resemble a traditional European city--Vienna or Paris in the nineteenth century, or, for that matter, Paris today. The poor and the newcomers are living on the outskirts. The people who live near the center--some of them black or Hispanic but most of them white--are those who can afford to do so.
"Developments like this rarely occur in one city at a time, and indeed demographic inversion is taking place, albeit more slowly than in Chicago, in metropolitan areas throughout the country. The national press has paid very little attention to it. While we have been focusing on Baghdad and Kabul, our own cities have been changing right in front of us....
"We are not witnessing the abandonment of the suburbs or a movement of millions of people back to the city all at once. But we are living at a moment in which the massive outward migration of the affluent that characterized the second half of the twentieth century is coming to an end. For several decades now, cities in the United States have wished for a "24/7" downtown, a place where people live as well as work, and keep the streets busy, interesting, and safe at all times of day. This is what urbanist Jane Jacobs preached in the 1960s, and it has long since become the accepted goal of urban planners. Only when significant numbers of people lived downtown, planners believed, could central cities regain their historic role as magnets for culture and as a source of identity and pride for the metropolitan areas they served. Now that's starting to happen, fueled by the changing mores of the young and by gasoline prices fast approaching $5-per-gallon. In many of its urbanized regions, an America that seemed destined for everincreasing individualization and sprawl is experimenting with new versions of community and sociability."