As the US administration struggles to help victims of Hurricane Katrina, it is faced with several urgent tasks.
Many of the evacuees need food, shelter and medical care
Almost a week after one of the worst disasters in the country's history, most of the people stranded in flood-hit New Orleans have been rescued.
Now relief organisations must judge how best to help the hundreds of thousands displaced from their homes across 90,000 square miles - many of them left with nothing.
Among those involved in the recovery effort are the Federal Emergency Management Agency (Fema), the American Red Cross, the US military and health workers.
RESCUING THE SURVIVORS
Local officials in New Orleans believe thousands of people may remain in the city despite an evacuation order.
Relief workers are making painstaking house-to-house searches through flooded buildings to find the remaining survivors.
They are also searching from the air in an attempt to spot people who have taken refuge in attics and on roofs.
Survivors have been urged to hang white or brightly coloured clothing from their homes to make them easier to find.
Volunteers with boats are helping to carry out people who may have been unable or unwilling to leave the city until now.
TRACING THE MISSING
As the majority of those stranded in New Orleans are removed to safety, the huge task of reuniting people with missing family or friends begins.
More than 75,000 people have signed up with the Family Links Registry, set up by the American Red Cross with other agencies.
It provides a website and telephone hotline where evacuees can register their whereabouts for concerned family and friends to read.
Those searching for missing people can post their details in the hope of news of them.
The authorities must find accommodation for the hundreds of thousands of people displaced from their homes in the wake of Hurricane Katrina.
The American Red Cross says it has opened more than 470 shelters in 12 states - Alabama, Arkansas, Florida, Georgia, Kentucky, Louisiana, Missouri, Mississippi, Oklahoma, Tennessee and Utah - sheltering more than 135,000 evacuees.
Spokeswoman Tara Lynch told BBC News: "Our efforts are still focusing on the sheltering and feeding of evacuees.
"At this moment, it's the basic necessities - a warm safe place, and toiletries, water and a hot meal."
More than 5,000 staff and volunteers from across the US were helping the relief efforts, she said.
Elsewhere, sports stadiums, military bases, civic buildings and business premises have been pressed into service as temporary accommodation.
Fema spokeswoman Linda Sacia told the BBC the agency had already started to move 50,000 travel trailers into the Gulf Coast region to house some of those left homeless.
Four cruise ships are also to be used to house and provide medical services to the elderly, disabled and ill, Fema has said.
Many of the evacuees may need to stay in temporary accommodation for months.
FEEDING THE EVACUEES
The American Red Cross has served more than 2.6 million hot meals and 3.4 million snacks over the course of five days.
Teams of volunteers, working in partnership with the Southern Baptists, are also manning emergency response vehicles, taking supplies of water, snacks and self-heating meals to people who have stayed with their damaged homes.
Some are permanently stationed near affected communities, giving them a place to turn for food and support.
COLLECTING THE DEAD
Emergency teams have begun the grim task of collecting potentially thousands of dead bodies from buildings and streets in New Orleans.
Refrigerated trucks and portable morgues have been brought to the region, and an operational centre has been set up in a warehouse in the town of St Gabriel, Louisiana.
Mortuary disaster response teams, comprising pathologists, coroners, forensic anthropologists and experts in fingerprinting, DNA and dental records, will seek to identify the bodies.
Hundreds of federal health officers and tonnes of medical supplies are on their way to the Gulf Coast.
The Department of Health and Human Services is setting up a network of up to 40 medical shelters, staffed by 4,000 medical personnel and offering 10,000 beds between them.
The first shelters are already treating patients in Baton Rouge, near New Orleans.
Large stocks of basic first aid supplies continue to be moved into the Gulf Coast area.
All patients and staff from the 11 top priority hospitals in New Orleans have been moved out, Fema says. Three other hospitals in the city are fully functioning so have not been evacuated.
Several countries have offered medical personnel and supplies should they be needed.
Health officials are keen to stop the spread of disease in the face of hot weather, mosquitoes and standing water holding sewage, petrol and chemicals.
DRAINING THE FLOODWATERS
Before New Orleans' vital pumping stations can be reactivated, the city has to be drained of water and its floodwalls and levees (embankments) repaired.
The US Army Corps of Engineers has said it is making good progress - but it could be up to 80 days before the process is complete.
Equipment at some of the pumping stations may have to be replaced if it is too badly damaged by flood water.
Once the city is drained, the authorities must begin the huge clean-up operation.
The American Red Cross has coordinated fundraising efforts over the past week.
Individuals, organisations and corporations, both national and international, had donated $409m by Monday.
The money will be used to fund current shelter and feeding operations, as well as longer term assistance such as counselling, mental health care and family support.
Red Cross spokeswoman Tara Lynch said: "This is the largest catastrophe in American history. It's bigger than one organisation, it's bigger than the Red Cross - it's people pulling together, working together."