If you live in a million-dollar condo in Philadelphia's ritzy Rittenhouse Square, your neighbors are likely to be equally well-off; the average household makes six figures. On the opposite side of the city, in misleadingly-named Strawberry Mansion, families earn less than half.
Philadelphia is one of the most income-segregated cities in the United States, but the same phenomenon is happening in most big cities. While there have always been richer and poorer neighborhoods, mixed-income neighborhoods are disappearing.
Since the 1970s, the number of people living either in a rich or poor neighborhood—versus mixed-income—has doubled. A new study, which analyzed the 95 largest metropolitan areas in the country, says that city planning is partly to blame.
The more restrictive a city's land use policies, the more likely it is to have segregated neighborhoods—especially enclaves of the super-rich. If local government is more involved in development, and more reviews and approvals are needed before new housing is built, a city's also more likely to be economically segregated. In part, that's probably because rich people are more likely to have a say in what a city does.
"I do think that wealthier people are more involved and more likely to get their way in local planning decisions," says Paavo Monkkonen, assistant professor of urban planning at UCLA and co-author of the study. "Getting a broader range of society involved in planning decisions is an important move, but also some reform of the planning system is necessary. We currently give a lot of influence to people willing to attend hearings and make their voices heard, but many people don't have time for that."
The more economically segregated a city becomes, the more likely it is that residents get stuck in a particular class. Poor children who grow up knowing at least a few richer friends have a much better chance of later making it out of poverty themselves.
"Mixed-income neighborhoods are important for two major reasons," says Monkkonen. "At the individual level, good social science shows that young people benefit from living near families with higher incomes—not only through peer effects but also better schools and services. At a bigger level, I think we need a society in which everyone is aware of people that are different from them in order to support strong welfare policies."
If policy creates economic segregation, it can also change it; the researchers found that in cities where planning had more state control, huge disparities between neighborhoods were less likely. Of course, wresting control away from local governments is a challenge.
"Policy could make a major difference in this tendency, but I don't see much to suggest that policy is moving in a direction towards more mixed income neighborhoods," he says. "Inclusionary zoning and other kinds of regulation could help but are infrequently applied and face opposition."
A handful of cities have deliberately moved some poor residents to rich neighborhoods—all as a result of lawsuits—and it seems to work well.