A crucial first step was taken when Congress approved a $10.5bn (£5.7bn) emergency aid bill covering 14 states, a down-payment of federal funds to help meet immediate costs of sheltering and feeding those displaced from their homes and helping them get back on their feet.
The money is already trickling through to states such as Texas, home to 250,000 evacuees and among the first to begin developing a formal plan to meet long-term needs. But while the money and political will appear to be there, nobody can say exactly what happens next.
"Everyone is trying to do the best they can but there's not a lot of answers right now," said David McEntire, a professor of emergency administration and planning at the University of North Texas.
"The problem is we've never had anything like this before so nobody knows how to deal with it. The good news is that everyone wants to make it work."
Rick Perry, the Texas governor, said: "We hope we can provide them with not just food, water, shelter and medicine, but dignity and decency as they pick up the pieces of their lives. What we are dealing with is an evacuation effort on a scale never seen before.
"It is an immense challenge and will continue to be so for a number of months but we will continue to receive our neighbours with open arms because we know they have nowhere else to turn."
Getting people out of the shelters and into proper accommodation is the top priority. In the states included in President George Bush's emergency declaration, the government will meet the cost of finding and paying for alternative housing. Cities with evacuees are working with housing associations to identify vacant houses and apartments, and in Dallas alone more than 1,000 people have already been found long-term accommodation.
Government money will also be used to provide mobile homes and, according to officials in Mississippi, the Federal Emergency Management Agency (Fema) has a fleet of 20,000 in Georgia awaiting delivery to the hardest hit areas.
One of the more creative solutions is a plan to move up to 7,000 evacuees from the Houston Astrodome, where an outbreak of diarrhoea is affecting children, to three chartered cruise liners moored in Galveston harbour for up to six months. Priority will be given to the elderly and families with young children, but the plan was put on hold yesterday when many decided they wanted to stay to try to locate lost family members first.
With evacuees sent to shelters in 22 states, and no accurate records of who went where, the Red Cross says it will be some time before everyone is reunited. The organisation has set up a website for evacuees to register their details and location and is offering free internet access in many shelters. "It's something that has really raised my spirits," said the Red Cross president, Marty Evans. "We're having great success in getting people to log on and make that match."
Getting displaced children back into education is another challenge and local authorities are opening their school gates. The Dallas school board yesterday added the Red Cross shelters at the Convention Centre and Reunion Arena to its regular school bus routes and has found classroom places for at least 500 children so far.
The United States Postal Service is attempting to redirect mail to evacuees and has given some of the larger shelters in Texas their own postal zip codes to speed delivery of documents such as insurance claim forms and disaster relief information.
Fema officials have also started arriving at shelters and encouraging other evacuees in hotels and private accommodation to register with them for immediate financial relief.
Mr Bush promised yesterday that people on social security would be able to pick up their cheques wherever they were. "Out of the darkness will come some light," Mr Bush said.
"Information is what's really needed now," Prof McEntire said. "People want to know when things are going to happen and in what form. There are a couple of websites that can help, but they're unofficial and they're not publicised. The bigger problem is that so many things are unknown, but the authorities need to get cracking on all of this and figure it out quickly."
