One of the least expected major trends of the last twenty years has been gentrification: old industrial zones in major cities have experienced a massive influx of young, educated-class residents, often raising rents and displacing black or Hispanic predecessors. This process is well-understood.
What is not as well known is where the displaced people go. While this isn't evidence, I noticed a trend in Census data from Chicago, and confirmed that similar trends exist in Boston, Philadelphia, and Washington. These cities are all dynamic and desirable, but only Washington has seen a large degree of overall population growth. I also found the same pattern in Rochester, New York, which is losing population.
Rochester is a great example of the archetypal American city. There's a "Center City" mostly surrounded by poor black & Hispanic neighborhoods, which are organized like slices of pie, each slice spreading outward toward the suburbs. Rochester, like most American cities, has an important exception: a wealthier, majority-white slice that preserves an old-fashioned urban lifestyle for whites who don't want to go suburban.
Figure 1 shows my hypothesis in the case of Rochester: that urban gentrification has been part of an elaborate cyclical dance which has young whites moving into run-down inner city neighborhoods, blacks moving into the next line of suburbs, and white families moving further out, into the exurbs. Each of these movements makes space for another, and none of them is complete and utter. Instead, most of the neighborhoods which take part in the dance become more integrated in the process.
Census data is shown by census tracts and in colors by race: blue is for Blacks, green is for Whites, orange is for Hispanics. In my analysis, I'll leave aside Hispanics (and Asians, in red), since their population is growing much faster than the U.S. average, making them more of a special case. Figure 1 shows Rochester with its tracts displayed by racial majority.
Tune in next time for city studies in support of this hypothesis.