How certain are you about those numbers? In the Discovery program they said 1/2 million people lived in New Orleans.
One is probably NO proper and one number is the metropolitan area.
I would imagine it would be over a million in the whole area.
That means at least a million people need shelter for months.
That is a lot of people.
Those numbers come from a study done on the Hurricane Ivan evacuation.
You can read a short version of it here:
http://www.colorado.edu/hazards/o/nov04/nov04c.html
Hmmm....I better ask which numbers you are referring to, should have before my first reply....possibly stepping into deep doo-doo here.