Middle-class neighborhoods are shrinking. They are losing ground in most regions nationwide. If fact, they are shrinking at more than twice the rate of the middle class itself. At the same time, poor and rich neighborhoods are expanding, as cities and suburbs have become increasingly segregated by income, according to a new study by Brookings Institute. It found that as a share of all urban and suburban neighborhoods, middle-income neighborhoods in the nation's 100 largest metro areas have declined from 58 percent in 1970 to 41 percent in 2000.

Expanding income inequality has been well documented in recent years, but the Brookings analysis of census data uncovered a much more accelerated decline in communities that house the middle class. It far outpaces the seven percentage-point decline between 1970 and 2000 in the proportion of middle-income families living in and around cities.

Middle-income neighborhoods, where families earn 80 to 120 percent of the local median income, have plunged by more than 20 percent as a share of all neighborhoods in cities like Los Angeles and Chicago. In all income levels, the primary goal of most families is to own their own home.