Hurricane Gustav hurtled toward collision with the Louisiana coast on Monday, bringing pounding rain, surging wind and the most direct threat to New Orleans since the devastation of Hurricane Katrina in 2005.
Nearly two million people fled the Louisiana coast in what is being called the largest evacuation in American history, and more than 11 million residents in five American states were braced for the impact from the fast-moving storm, which was expected to make landfall on Monday morning local time around New Orleans.
Officials have shut down the area's vital oil production facilities from Texas to New Orleans. The region that pumps a quarter of the United States' oil supply and 15% of its natural gas.
By Sunday night, the streets of New Orleans were ghostly quiet after 95% of the city's 239,000 population responded to desperate calls by officials for a sweeping evacuation.
Only 10,000 people were believed to have stayed behind in New Orleans. Police and national guard troops patrolled the empty city as a curfew went into effect in a bid to prevent looting.
An estimated 1.9 million people had fled coastal areas.
By early Monday, the outer bands of the storm were nearing the coast and had kicked up strong, gusting winds south of the city that were expected to gather force through the morning. The storm packed maximum sustained winds of 185 km/h, making it a Category 3 storm, the US National Hurricane Center said.
Forecasters said Gustav could still strengthen but said the hurricane was no longer expected to be a Category 4 hurricane on the five-step Saffir-Simpson scale.
Even so, a storm surge of up to 4.3 metres could threaten the same levees that failed during Hurricane Katrina. Federal officials say the levees protecting New Orleans are stronger now but still have gaps.
Hurricane Katrina struck on 29 August 2005, flooding 80% of the city, killing 1,500 people in five states and costing $US80 billion. Katrina was a Category 3 when its 8.5-metre storm surge burst levees. New Orleans degenerated into chaos as stranded storm victims waited days for government rescue and law and order collapsed.
Hurricane Gustav was expected to swamp parts of Louisiana, Mississippi, Arkansas and Texas with up to 300mm of rain and could spin off isolated tornadoes, forecasters said.
The US Coast Guard reported the first storm-related death in Florida, where a man fell overboard as his craft ran into heavy waves. Three others were believed to have died in hospital evacuations in Louisiana.
Bush to oversee relief efforts
President George W Bush and vice-president Dick Cheney, accused of a slow and botched response to Katrina's chaos, said they would not attend this week's Republican National Convention in St. Paul, Minnesota.
Instead, Mr Bush will travel to Texas on Monday to oversee emergency response efforts.
Republican candidate John McCain curtailed activities for Monday's opening day of the convention that will formally nominate him to face Democratic nominee Barack Obama in the November election.
Mr McCain headed to the Gulf to survey emergency preparations and cancelled political speeches for the opening day of his nominating convention to avoid a festive atmosphere.
80 dead in Caribbean
The storm 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.
Cuban television reports that the Isle of Youth was devastated.
