Trading Places:

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.

A fascinating read for those who like to think about how our cities evolve.