CHARLOTTE, N.C. — Over the last four years, David and Alfreda Belton have been working toward the American Dream.

Married in 1987, the Beltons--who together earn about $80,000 a year--now live in a spacious three-bedroom, art-laden home in one of this area's poshest suburbs. Their 2-year-old son, Cameron, attends a private day-care facility. And they have two cars.

"I can't complain," David Belton says. "I want to do better in the future, but right now I'm where I want to be."

The Beltons' happy tale may seem like just another American success story, but there is an extra element: The Beltons are black. Although the bulk of national attention recently has focused on the underclass, the Beltons' story illustrates that there also is a sizable black middle class and it has mushroomed.

Over the last three decades, the number of black Americans officially counted as middle class--or "affluent" in the language of the Census Bureau--has grown by almost 400%, more rapidly than any other racial category in American society. More than 1 million black households are listed by the Census Bureau as "affluent," with incomes of $50,000 or more, and they are enjoying a middle-class lifestyle that was beyond the reach of their parents and grandparents. The figure, about 14% of the nation's black population, is up sharply from 1967, when only 266,000 black households, or 5.8% of the total, were considered affluent.

The rapid expansion raises the possibility that the broadening of the black middle class may lead to a new order in politics, civil rights and social patterns in America. And the upscale, typical American lifestyle that middle-class status brings could alter public perceptions of all blacks as well.

"The black middle class is a kind of bellwether of black progress," says Bart Landry, a sociologist at the University of Maryland and author of a 1987 study of black upward mobility since the 1960s. "Its very existence gives hope to blacks in other classes that they or at least their children might yet reach the American Dream."

The gains reflect what William P. O'Hare, a social demographer at the University of Louisville's Urban Research Institute, calls "the first fruits of the 1960s' civil rights movement": Civil rights laws and affirmative-action programs have dramatically broadened job prospects for young black professionals in almost every white-collar occupation. And greater educational opportunities have finally enabled young blacks to obtain the qualifications denied their parents and grandparents.