Defining Income Diversity: In our three-decade retrospective analysis, we sought to establish a framework to describe patterns of neighborhood economic change. Citywide, nearly all communities showed a substantial decrease in the number of families with moderate annual income ($38,622 - $78,825) between 1970 and 2000. (All income figures are inflation adjusted to 2004 dollars.) The variable elements of income diversity over time can thus be expressed in terms of two additional factors:

1. whether the number or percent of high income (>$78,825) families in a neighborhood is increasing;
2. whether the number or percent of low income (<$38,622) families in a neighborhood is increasing.