Analysis of 1970 to 2000 decennial census data for families and neighborhoods in the 100 largest metropolitan areas, and in the cities and suburbs of 12 selected metropolitan areas, finds that:
- Middle-income neighborhoods as a proportion of all metropolitan neighborhoods declined from 58 percent in 1970 to 41 percent in 2000. This dramatic decline far outpaced the corresponding drop in the proportion of metropolitan families earning middle incomes, from 28 percent in 1970 to 22 percent in 2000.
- Between 1970 and 2000, lower-income families became more likely to live in lower-income neighborhoods, and higher-income families in higher-income neighborhoods. Only 37 percent of lower-income families lived in middle-income neighborhoods in 2000, down from 55 percent in 1970.
- The proportion of neighborhoods that were middle-income shrank faster than the proportion of families that were middle-income in each of 12 large metropolitan areas examined. Among the 12 metro areas, Los Angeles-Long Beach, Baltimore, and Philadelphia experienced much more dramatic declines in middle-income neighborhoods than San Antonio and Louisville.
- Only 23 percent of central-city neighborhoods in the 12 large metropolitan areas had a middle-income profile in 2000, down from 45 percent in 1970. A majority of families (52 percent) and neighborhoods (60 percent) in these cities had low or very low incomes relative to their metropolitan area median in 2000.
- A much larger proportion—44 percent—of suburban neighborhoods in the 12 metropolitan areas had a middle-income profile in 2000. Yet this proportion fell over the 30-year period, too, from 64 percent in 1970, accompanying a smaller decline in suburban middle-income families. Suburban middle-income neighborhoods were replaced in roughly equal measure by low-income and very high-income neighborhoods.
Although middle-income families have declined considerably as a share of the overall family income distribution, it is noteworthy that middle-class neighborhoods have disappeared even faster in metropolitan areas, especially in cities. This trend suggests increased sorting of high- and low-income families into neighborhoods that reflect their own economic profiles, and increased vulnerability of middle-class neighborhoods "tipping" towards higher- or lower-income status. The resulting disparities among neighborhoods create new challenges for policies to enhance household mobility, improve the delivery of key public services, and promote private-sector investment in struggling locales.