As the storm drew near, streets along Mississippi's Gulf Coast were all but deserted, and miles of homes and businesses, including its 12 floating casinos, were boarded up.

Only patrol cars and an occasional luggage-packed car or van could be seen passing Gulfport's "Welcome to the Gulf Coast" billboard.

New Orleans scrambled to get people out of harm's way, putting the frail and elderly in the cavernous Louisiana Superdome and urging others to move to higher floors in tall buildings.

Of the roughly 2 million who fled the path of the storm, often in bumper-to-bumper caravans on highways turned into one-way evacuation routes, 1.2 million were from greater New Orleans, a city particularly vulnerable to hurricanes because it sits below sea level, between the Mississippi River and Lake Pontchartrain.

An 11th-hour turn may have spared the bowl-shaped city a direct hit, but officials warned that the levees and pumping stations that normally hold back the water may not be enough to protect the city.

"If we turn up dead tomorrow, it's my fault," said Jane Allinder, who stayed stubbornly behind at her daughter's French Quarter doll shop to keep an eye on her cat.

Police began clearing people off the streets, enforcing a 2 p.m. curfew.

"I think it's safe to say we will have flooding in this city," said Mayor Ray Nagin. However, he contradicted a statement from his emergency preparedness director that the city needed at least 10,000 body bags to handle possible drowning victims.

Thousands of tourists were believed stranded in New Orleans, along with 100,000 mostly inner-city residents without cars. The mayor advised them to resort to "vertical evacuations," suggesting they take shelter in buildings taller than two stories. If that is not possible, he said, they should go into an attic and take equipment with them that would allow them to cut through the roof and get out.

Rick Pfeifer, a salesman from Washougal, Wash., was stuck in New Orleans with no flights out and no cars to rent after arriving earlier this week for a National Safety Congress convention. His storm rations included as many chips, pretzels and bottled water as he could buy.

"I'm going to ride it out in the high-ground area of the city," he said wryly. "Fourth floor in a good hotel, with a good bar."

Frail, elderly and sick residents unable to get out were moved to the 72,000-seat Louisiana Superdome, where 200 cots in upper-deck concourses supplanted the dome's usual tenant, the New Orleans Saints.

LuLinda Williams wept after dropping off her bedridden grandmother, who is on oxygen, at the Superdome. Only one family member was allowed to stay with each patient, so Williams left her daughter.

"I thought they'd let the family stay with them," Williams said. "Where are the rest of us supposed to go now? How are we supposed to know she's OK?"

Nagin later said the dome would also be opened as a one-night last resort for able-bodied storm refugees. The last time that happened during Hurricane Georges in 1998, the 14,000 refugees nearly did more damage than the storm itself. Countless televisions, seat cushions and bar stools were stolen, and workers spent months cleaning graffiti off the walls.

Winds howled across Louisiana's bayous with enough force to topple trees and knock out power.

"We heard a loud pop, and I thought, not already," said Harold Plaisance, who had been sitting on the porch watching the storm in the fishing village of Lafitte.