More than a million people have fled Louisiana as Hurricane Gustav moves toward New Orleans.
Highways out of New Orleans have been crammed since before dawn on Sunday. Gustav could reach the coast as early as midday Monday.
State governor Bobby Jindal said that more than a million people are on the move.
New Orleans mayor Ray Nagin has ordered residents to leave the city. A curfew is now in place.
A hurricane watch is in place from Texas along to the Alabama-Florida border.
Gustav is slightly weakened, but still a Category 3 storm with winds near 205 km/h. Earlier, it hit Cuba after claiming at least 81 lives across the Dominican Republic, Haiti and Jamaica.
More than 250,000 were evacuated from western parts of mainland Cuba before the storm arrived. Cuban television reported that the Isle of Youth was devastated.
New Orleans marked the third anniversary of Hurricane Katrina on Friday.
Katrina hit the coast near New Orleans as a Category 3 hurricane on 29 August, 2005, with wind speeds up to 209km/h.
Its storm surge broke through levees and flooded 80% of the city. About 1,500 people were killed on the US Gulf Coast. Damage amounted to $US80 billion.