Here is another way to look at the gap between the rich and poor in the United States: the percentage of Americans living in middle-income neighborhoods has shrunk in recent decades.

In 2007, nearly a third of American families — 31 percent — lived in either an affluent neighborhood or a mainly low-income one, up from just 15 percent in 1970, according to the study conducted by Stanford University, and released in partnership with the Russell Sage Foundation and Brown University.

Meanwhile, 44 percent of American families lived in middle-class neighborhoods in 2007, down from 65 percent in 1970…

For the study, researchers used data from 117 metropolitan areas, each with more than 500,000 residents. In 2007, those areas were home to 197 million people — or two-thirds of the US population.

This study covers about two-thirds of the American population. I assume the study is restricted to larger metropolitan areas because of how the researchers defined a neighborhood but couldn’t they adapt to smaller cities in order to represent more of the US population? Also thinking about the research methods, I hope the researchers used analogous cutoff points for these different classes in 1970 and 2007.

Moving past methodological issues, this does bring to light an interesting issue: how many Americans experience residential segregation based on social class? Of course, race and social class is linked. Do Americans care that people of different income strata live in completely different areas? Based on American history, I would say no: Americans don’t seem terribly concerned about concentrated poverty or pockets of affluence. If you have money, it is generally expected that you go live with people who also have money. You might provide incentives for the classes to mix (example: mixed-income neighborhoods on the site of former housing projects) but this is rare.

It would be interesting to see a breakdown here between cities and suburban areas. Some of the earliest American sociological research focused on these disparities in the city, such as Zorbaugh’s work The Gold Coast and the Slum where the rich and poor lived in incredible proximity but rarely mixed. Is class-based residential segregation higher in the suburbs?