FILE - In this Sept. 1, 2005 file photo, residents wait on a rooftop to be rescued from the floodwaters of Hurricane Katrina in New Orleans. At an estimated $81 billion in property damage, it is the costliest natural disaster in U.S. history. But to many, especially to those in greater New Orleans, this catastrophe was anything but an act of God.
(AP Photo/David J. Phillip, Pool, File)