“We came back, we tried,” he said. “It’s really draining, and at a certain point you sit down and you say, ‘We don’t have to go through this.’ ”

Image GOING Kasandra Larsen and Dylan Langlois on their last day in New Orleans. I think a lot of us are feeling under siege, Mr. Langlois said. Credit... Lee Celano for The New York Times

As a city in flux, New Orleans remains statistically murky, but demographers generally agree that the population replenishment after the storm, as measured by things like the amount of mail sent and employment in main economic sectors, has leveled off. While many poorer residents have moved back to the city, the “brain drain” of professionals that the city was experiencing before the storm appears to have accelerated.

Some say the overall effect is negligible. Greg Rigamer, a demographer who has done work for the city, said that the lack of housing had constrained the recovery, but that many residents remained fully committed to the city.

“The pattern in is certainly stronger than the pattern out,” Mr. Rigamer said.

But in December, the number of houses on the market peaked at a high not seen since the late 1980s, while the number of sales has trended downward since last June, according to data tracked by the Brookings Institution in Washington. Statistics kept by commercial moving companies show a net loss to New Orleans. Employers say they have raised salaries for skilled workers.

One oft-cited survey by the University of New Orleans found that a third of residents, especially those with graduate degrees, were thinking of leaving within two years.

Susan E. Howell, who conducted the survey, cautioned that the sample was small and that the poor were underrepresented. There are indications that low-income New Orleanians — those who will need the most help from a cash-strapped city —are making their way back, despite a lack of affordable housing, piling into relatives’ homes and trailers.

U-Haul, the rental company that is more affordable than commercial movers, has had more inbound trucks than outbound, according to the company’s records, and the number of public school children and new applications for food stamps in Orleans Parish are rising. In Houston, a task force that helps Hurricane Katrina residents resettle has paid more than $1 million in moving expenses for 350 families returning to New Orleans.