The first priority is to evacuate hospitals and shelters, including people remaining at the New Orleans Superdome and the Ernest M. Morial Convention Center, about a mile away, where relief supplies and troops arrived Friday afternoon.
River traffic was expected to resume on a portion of the Mississippi River, a Coast Guard spokeswoman said.
The U.S. Department of Homeland Security, the Air Traffic Association and the Department of Transportation said "Operation Air Care" would airlift more than 25,000 stranded residents from New Orleans' Louis Armstrong International Airport to relocation centers in Texas and elsewhere.
"DHS is truly grateful to the airlines for their immediate and generous contribution to help us to bring hurricane victims to safety," said Deputy Secretary of Homeland Security Michael Jackson.
More than a dozen U.S. airlines, Air Canada and cargo carriers will participate in the unprecedented airlift.
"We've cleared the runways and are watching the skies to make sure these humanitarian flights get in and out safely," said U.S. Secretary of Transportation Norman Y. Mineta.