Middle- and upper-class neighborhoods like Gentilly, Pontchartrain Park and others in East New Orleans that were home to black professionals were devastated by flooding, says Karen B. DeSalvo, professor of medicine at the Tulane School of Medicine. Methodist Hospital, where many black physicians worked, was shut down. In July 2010, the city agreed to buy and reopen the facility.

The slow trickle of blacks back to New Orleans has had a pernicious spiraling effect: Pastors can't open churches if there are few congregants, and lawyers and doctors who had largely a black clientele are hard-pressed to keep their doors open.

For some African Americans, the disruptions created by Katrina revealed possibilities. Sheila and Ronnie Burns own a courier service and parking management company that had combined revenues of about $2 million to $3 million annually pre-Katrina. The flooding drove out many of their employees and damaged or destroyed clients' offices. But the Burns' national network of courier services helped them rebuild, and law firms, a vital part of their customer base, use their services again. Consequently, the Burns' overall revenue grew to $3 million to $4 million a year.

The Burns' son moved back to New Orleans to work in the family business, part of an influx of young people moving to the city post-Katrina. Telley Madina, 29, left with his family during the storm but saw opportunities afterward. Madina, who runs a political consulting firm, says Katrina leveled the playing field initially, especially for younger people. But he feels the city still lacks the conditions necessary to spur the growth of a black middle class. He says that Atlanta has dual-income households of $100,000, people who go on vacation, have savings and get dance lessons for their kids. By contrast, he says, "New Orleans will be a city of old people looking to retire or young people with nothing to lose. There is no middle class of African Americans."

Many professionals who have returned find themselves in situations like that of entrepreneur David St. Etienne. The main client of his tech business was the Orleans Parish school system. But the restructuring has reduced his revenues by two-thirds of what it was before Katrina.

"We had to start from scratch. Our clients are small businesses, private schools, no particular industry," St. Etienne said. "Katrina decimated the black middle class and business class. It was harder for us to start in beginning, and it's harder for us to start after Katrina. The pie has shrunk, and it's even tougher."

Neela Banerjee is a former New York Times reporter based in Washington, D.C.