After a dramatic increase in the concentration of poverty between 1970 and 1990, there were substantial declines in the 1990s related to a booming economy and changes in housing policy that favored decentralized forms of housing subsidies. Unfortunately, the concentration of poverty has surged once again since 2000.
A new report issued jointly by the Center for Urban Research and Education (CURE) and the Century Foundation, Concentration of Poverty in the New Millennium, shows that concentrated poverty has returned to—and in some ways exceeded—the previous peak level of 1990. However, there are substantial differences in how concentrated poverty is manifested in the new millennium. In particular, it is worth noting that the residents of high poverty neighborhoods are more demographically diverse than in the past; that smaller metropolitan areas and cities experienced the fastest growth, rather than the largest metro areas as was common in the past; and that, within cities, high-poverty neighborhoods are more decentralized and disconnected, with unknown implications for the residents of these areas. The report also discusses why an understanding of the spatial dimension is critical to addressing the problems caused by poverty.
Also see this blog post, which addresses the impact of concentrated poverty on student achievement.