Even before the evacuation order, hotels closed, and the airport prepared to follow suit. Nagin told tourists to leave. Homeland Security Secretary Michael Chertoff planned to travel to Louisiana on Sunday to observe preparations. 

Residents board a bus to evacuate New Orleans, Louisiana, ahead of Hurricane Gustav August 30, 2008. City officials could order a mandatory evacuation of New Orleans starting early on Sunday, New Orleans Mayor Ray Nagin said on Saturday. [Agencies]

As part of the evacuation plan New Orleans developed after Katrina, residents who had no other way to get out of the city waited on a line that snaked for more than a mile through the parking lot of the city's main transit terminal. From there, they were boarding motor coaches bound for shelters in north Louisiana.

"I don't like it," said Joseph Jones Jr., 61, who draped a towel over his head to block the blazing sun. "Going someplace you don't know, people you don't know. And then when you come back, is your house going to be OK?"

Jones had been in line for 2 hours, but he wasn't complaining. During Katrina, he'd been stranded on a highway overpass.

Others led children or pushed strollers with one hand and pulled luggage with the other. Volunteers handed out bottled water, and medics were nearby in case people became sick from the heat.

Unlike Katrina, when thousands took refuge inside the Superdome, there will be no "last resort" shelter, and those who stay behind accept "all responsibility for themselves and their loved ones," said the city's emergency preparedness director, Jerry Sneed.

Yet the presence of 2,000 National Guard troops that were expected to join 1,400 New Orleans police officers patrolling the streets following the evacuation, along with Gov. Bobby Jindal's request to neighboring states for rescue teams, suggested officials were expecting stragglers.

Standing outside his restaurant in the city's Faubourg Marigny district, Dale DeBruyne prepared for Gustav the way he did for Katrina, stubbornly.

"I'm not leaving," he said. DeBruyne, 52, said his house was stocked with storm supplies, including generators. "I stayed for Katrina," he said, "and I'll stay again."

Advocates criticized the decision not to establish a shelter, warning that day laborers and the poorest residents would fall through the cracks.

About two dozen Hispanic men gathered under oak trees near Claiborne Avenue. They were wary of boarding any bus, even though a city spokesman said no identity papers would be required.

"The problem is," said Pictor Soto, 44, of Peru, "there will be immigration people there and we're all undocumented."