CAMBRIDGE, Mass.
Advocates for the poor have protested President Bush's $350 billion tax cut on many grounds, notably its selective use of the per-child tax credit. But few have discussed its potential effect on one of the more remarkable long-term economic trends of the last decade: the decline in concentrated poverty in America.

A recent report for the Brookings Institution by a University of Texas social scientist, Paul Jargowsky, revealed that the number of people residing in high-poverty neighborhoods decreased by 24 percent, or 2.5 million people, from 1990 to 2000. Moreover, the number of such neighborhoods ? the study defined them as census tracts with at least 40 percent of residents below the poverty level ? around the country declined by more than a quarter.

The news has been greeted as a major step forward for inner-city blacks, because their neighborhoods tend to feature the highest levels of concentrated poverty. To some extent this is true, although perhaps not in the way either the political left or right are spinning it. And, as promising as the findings are, they do not signify that we've found a magic bullet in the war on poverty.

… Almost 30 years ago, the African-American economist Vivian Henderson pointed out that "the economic future of blacks in the United States is bound up with that of the rest of the nation." So, just as blacks suffered greatly during the decades of growing separation between haves and have-nots, they benefited considerably from the incredible economic boom in the last half of the 1990's, which not only substantially reduced unemployment, including black unemployment, but sharply increased the earnings of all low-wage workers as well.

Undoubtedly, if the robust economy could have been extended for several more years, rather than coming to an abrupt halt in 2001, concentrated poverty in inner cities would have declined even more.

This cannot be proved now; data on concentrated poverty are provided only by the decennial census. But the Brookings report clearly shows that the favorable trend of the 1990's may be temporary rather than long term. Unemployment and individual poverty rates are on the rise again; more than 2.4 million jobs have disappeared in the last two years. And given the continuing increase in the Hispanic population, the number of high-poverty barrios is likely to grow rapidly in a sluggish economy.