A new study conducted by researchers associated with Stanford University and the US2010 Initiative finds fewer Americans living in middle income neighborhoods and more rigid segregation by income and class. Segregation by class is particularly prominent among racial minorities. Overall, the proportion of families living in middle income neighborhoods declined, from 65% in 1970 to just 44% by 2007. Segregation by family income rose since 2000 in 89% of metropolitan areas evaluated in the research study.
Researchers drew data on family income from the U.S. Census decennial census (1970-2000) and the American Community Survey (ACS) five-year data (2005-2009). These data were used to estimate income segregation in metropolitan areas with a population of at least 500,000. Within each metropolitan area, the researchers classified areas where median incomes were greater than 150% of median as affluent; areas where median incomes were less than 67% of the median were classified as poor. Income segregation was estimated based on income distribution at the neighborhood level compared to income distribution across the metropolitan area.
Since 1970, the proportion of families living in middle income census tracts has declined, with more families living in neighborhoods at either extreme. Between 1970 and 2007, the proportion of families living in affluent neighborhoods rose from 7% to 14%. Similarly, the proportion of families living in poor neighborhoods rose from 8% to 17%. On the whole, neighborhoods have become increasingly income stratified, with 31% of families living on the extreme ends of the income distribution by 2007.
In the 2000s, families on both extremes of the income spectrum have become increasingly isolated from middle income families. The isolation of the affluent (top 10% of families, by income) has become greater than even the isolation of the poor, a finding that has profound implications for the concentration of resources by neighborhood.
Among minority families, income segregation is pronounced; low income Black households are significantly more isolated from middle-class Black households, compared to the levels of segregation among White families. By 2007, income segregation among Black families was 60% greater than among White families. Researchers hypothesize that this may be in part due to the disproportionate effects of the subprime mortgage market, but further analysis is needed to explore these trends.
The report, Growth in the Residential Segregation of Families by Income, 1970-2009, is available at: http://www.s4.brown.edu/us2010/Data/Report/report111111.pdf