http://news.bbc.co.uk/1/hi/world/americas/7590426.stmNew Orleans residents flee storm
New Orleans residents have been fleeing in their thousands after the city's mayor ordered an evacuation ahead of Hurricane Gustav's expected landfall.
Roads out of the Louisiana port have been crammed with traffic and authorities have been helping those unable to leave by their own means.
Gustav, set to hit the US Gulf Coast on Monday, was described by Mayor Ray Nagin as "the storm of the century".
It comes three years after Hurricane Katrina devastated New Orleans.
In 2005, three-quarters of the city was flooded after a storm surge breached its protective levees. More than 1,800 people died in coastal areas.
The BBC's Kevin Connolly, in New Orleans, says that on the main roads out of the city, traffic now flows in the same direction along both carriageways, carrying a stream of family vehicles to the relative safety of the north.
Many of the city's major hotels are shutting down and tourists have been advised to leave before the airport closes too, our correspondent says.
At the city's main transit terminal, reports said a line snaked for more than a mile as residents waited to board buses bound for shelters in north Louisiana and beyond.
Louisiana Governor Bobby Jindal, in New Orleans to observe the evacuation, said about 700 people an hour could be flown out of the city.
Gustav weakened to a category three storm (with winds of up to 125mph; 201km/h) after hitting Cuba overnight, but was expected to regain strength in the Gulf of Mexico before making landfall again.
A hurricane watch is place from Texas along to the Alabama-Florida border.
The hurricane has already claimed the lives of more than 80 people in the Caribbean, causing widespread damage in Haiti, the Dominican Republic and Jamaica over the past week.
At least 300,000 people were evacuated in Cuba as the storm brought extensive flooding and some severe damage, but no reports of deaths.
'Ensure you have an axe'
Mayor Nagin told a televised news conference the storm was "so powerful" and growing more powerful every day.
FLASHBACK TO KATRINA
Katrina struck US Gulf Coast in August 2005 as a category three storm, killing more than 1,800 people
New Orleans was 80% flooded after storm surge breached protective levees
US Government was blamed for slow, botched response that exacerbated disaster
Hundreds of thousands of people were displaced
"I'm not sure we've seen anything like it," he told reporters at City Hall.
He warned that in the West Bank area of New Orleans, the highest levees were just eight to 10 feet, and were at risk from storm surges that could be as high as 24 feet.
The floodwalls of the Harvey Canal - a waterway designed to protect residents from surges in Lake Pontchartrain - were not yet completed, the mayor said, warning that water would "punch through holes" and flood nearby areas.
"If you are stubborn enough, if you are not taking this as seriously as we need you to take it, and if you decide to stay; you are on your own," he said.
"Anyone who decides to stay, I'll say it like I said it before Katrina: make sure you have an axe, because you will be carving your way, or busting your way out of your attic to get on your roof with waters that you will be surrounded with in this event."
'We're feeling very insecure'
Hundreds of thousands of people have already fled the city, clogging roadways, emptying petrol stations of fuel and jamming phone networks.
Sarah Debacher, who has lived in New Orleans for 10 years and was preparing to leave her home for the fourth time, told the BBC she was feeling "very insecure".HURRICANE CATEGORIES
FIVE: Winds over 155mph (249km/h). Storm surge more than 18ft (5.4m) above normal. Only three such US landfall hurricanes - Labour Day 1935, Camille 1969 and Andrew 1992
FOUR: Winds 131-155mph. Storm surge 13-18ft
THREE: Winds 111-130mph. Storm surge 9-12ft. Katrina hit New Orleans as a three.
TWO: Winds 96-110mph. Storm surge 6-8ft
ONE: Winds 74-95mph. Storm surge 4-5ft
Source: Saffir-Simpson Scale/US National Hurricane Centre
"The failure of the federal levees after Hurricane Katrina meant that we experienced devastation that we shouldn't have experienced," she said.
"Frankly we don't have a lot of faith in the work that's been done to repair the damage that was caused by those failures and by the storm."
City, state and federal officials will be mindful that the reaction to Gustav will be closely scrutinised, not least because the slow and badly co-ordinated response to Katrina was blamed for exacerbating the 2005 disaster.
Eric Blake, from the US National Hurricane Center in Florida, told the BBC Mr Nagin may have overstated the size of the hurricane.
"I think that may be a bit of an exaggeration. I mean, they already had Hurricane Katrina, and right now this is no Hurricane Katrina. But we still think it will be a large and powerful hurricane and a significant threat."
Republican convention doubts
Republican Party presidential hopeful John McCain and his running mate Sarah Palin were travelling to Mississippi on Sunday to observe storm preparations.
The Republican National Convention is due to open on Monday in Minnesota and officials are considering what to do about the gathering.
Mr McCain hinted there might be changes to the tone of the event, rather than a cancellation.
He told Fox News: "You know it just wouldn't be appropriate to have a festive occasion while a near tragedy or a terrible challenge is presented in the form of a natural disaster, so we're monitoring it from day to day and I'm saying a few prayers, too."
The White House said concerns over Gustav meant President Bush was unlikely to attend the convention for his scheduled speech on Monday.
Oh sh*t.
