As US  poverty rates crept up in  the early 2000s, so did the number of Americans living in high-poverty neighborhoods. In the 100 biggest metro areas, the Census Bureau estimates,  poverty grew from  11.3 to 12.1 percent between 2000 and 2005-09 (average rate across the five years). Meanwhile, the percentage of people living in neighborhoods with poverty rates over 30 percent grew from 7.9 to 8.4 percent while the share in moderate-poverty neighborhoods of 20 to 30 percent rose from 9.9 to 11.2 percent.

Let’s unpack these numbers.

In these 100 metros, on average, every percentage-point increase in the local poverty rate made the share of people living in high-poverty neighborhoods jump by 1.8 points (see chart). Consider metro Memphis, where the poverty rate grew 2.7 points, but the share of residents living in neighborhoods with poverty rates over 30 percent grew 5.6 points.  Why? As metropolitan poverty grows, at least some neighborhoods tip into “high-poverty” status, meaning that everyone in the neighborhood slips into concentrated poverty. In metro New York, by contrast, poverty fell by just over a percentage point, spurring a 2.1-point drop in the percentage of its residents living in high-poverty neighborhoods.

As metro poverty grows, concentrated poverty grows faster

Changes in the 100 biggest metros, 2000 to 2005-09 (average)

Federal policymakers usually take on concentrated poverty through specific initiatives, such as HOPE VI and the new Choice Neighborhoods program. These numbers show that that broader-based efforts to stabilize and grow the incomes of low-income households everywhere will also pay off in lower neighborhood poverty rates and help relax poverty’s grip on vulnerable people.