NEW ORLEANS — Bill Rau, the 45-year-old owner of a French Quarter antique shop that sells diamonds and 18th century clocks, flew his family to Dallas on Sunday, not because he knew anyone there but because it was the only way he could get out of town.
He thought about driving but feared that Hurricane Katrina -- a menacing storm with sustained winds of at least 160 mph expected to strike before 7 this morning -- would catch up with him while he sat in traffic.
So he spent $3,000 and bought the only tickets he could find: six one-way, first-class seats to Dallas.
John Higgins was struggling in a different way. The 49-year-old man hobbled through New Orleans as the wind picked up, carrying what he owned -- a purple comb, a radio and a pack of instant coffee -- on his back.
The homeless shelter where Higgins usually stayed had closed because of fears that Katrina would destroy it. He had no car, no money and nowhere to go, so he was trying to make his way to the Louisiana Superdome, the downtown arena that had hosted Super Bowls and Bob Hope but was pressed into service as a storm shelter.
To some degree, Katrina was an equalizer, leaving Rau and Higgins clawing their way to safety.
But it also served as a reminder that this is a city of haves and have-nots. And on Sunday, by and large, the former got out of town -- about 1 million of the metropolitan area's 1.6 million people, officials said -- and the latter were left behind.
"Ain't that life?" Higgins asked.
Those who remained in New Orleans, a large part of which sits below sea level, will probably wake this morning to calamity.
If Katrina maintains its strength, it will arrive as a Category 5 hurricane, the most powerful. Only three Category 5 hurricanes have struck the United States. The last was Hurricane Andrew, which pummeled Florida in 1992.
Katrina grew after hitting Florida's east coast Thursday as a Category 1 hurricane, causing 11 deaths before blowing across the state into the Gulf of Mexico, lifting fuel from the warm water.
New Orleans Mayor C. Ray Nagin ordered a mandatory evacuation for the first time in the city's history, calling the storm a "once-in-a-lifetime event."
"The city of New Orleans has never seen a hurricane of this magnitude hit it directly," Nagin said as he and Gov. Kathleen Babineaux Blanco announced the evacuation at a news conference. "This is awesome."
The National Hurricane Center in Miami issued dire warnings about the storm's magnitude. By midnight, Katrina was moving northwest at 10 mph and had sustained winds of 160 mph and higher gusts. Hurricane-force winds extended 105 miles in every direction from the center, and tropical-storm-force winds stretched out 230 miles. The eye of the hurricane measured about 30 miles in diameter.
The Louisiana coast could experience storm surges as high as 28 feet, 15 inches of rain and tornadoes, the National Hurricane Center said. A 28-foot storm surge would be the highest ever recorded, officials said.
Katrina had developed into what leading forecasters had been worrying about for years: a mammoth storm bearing down on a densely populated coastal flat.
Bill Read, a meteorologist at the National Hurricane Center in Miami, said Katrina was the fourth-largest Atlantic hurricane ever measured, behind Gilbert in 1988, Allen in 1980 and the 1935 Labor Day hurricane, which occurred before tropical storms were named.
Officials said Katrina rivaled Hurricane Camille, a notorious Gulf of Mexico storm that smashed into the Mississippi coast in August 1969 -- wiping out entire stretches of shoreline, destroying more than 5,600 homes and killing 259 people.
"At the moment, this one is stronger than Camille," Read said. "It's got everything we warn about going for it: It's large and it's going for vulnerable areas of the coast, so storm surge will be bad."
Nagin said as many as 30,000 people had sought shelter at the Superdome by 5 p.m. and thousands more were in line, though the city had repeatedly urged residents to consider the arena a shelter of "last resort." About a dozen other shelters had been opened, although some were full and people were turned away.
The mayor said people should be prepared to stay in shelters for as long as five days and should bring their own provisions. If power went out, electricity could remain off in parts of the city for six weeks, Nagin said.
The Federal Emergency Management Agency, which coordinates disaster assistance, was sending teams with food, water, ice and generators to areas across the southeastern United States, said Natalie Rule, a spokeswoman.
In addition to supplies, the federal agency has prepared search-and-rescue teams and disaster medical units. "They'll move in as soon as it's safe," Rule said.