Tropical storm Isaac is expected to weaken further as it heads north on Thursday, after causing significant damage to the US Gulf Coast.
However, it did not approach the scale of Katrina, a Category 3 hurricane which devastated New Orleans on 29 August 2005, killing more than 1800 people.
The National Hurricane Center says Isaac, a former Category 1 hurricane, is likely to become a tropical depression and move over southern Arkansas.
Many further north will hope that Isaac brings rain desperately needed to ease a drought in the centre of the country, where summer crops have been ravaged and many rivers and dams are critically low, Reuters reports.
New Orleans mayor Mitch Landrieu said a $US14.5 billion system built for the city by the Army Corps of Engineers - an array of walls, floodgates, levees and pumps - had performed "exactly as it should".
More than 730,000 residents of Louisiana and Mississippi were still without power.
President Barack Obama declared the impact on Louisiana and Mississippi major disasters and ordered federal aid to supplement state and local recovery efforts.
There was a heavy security presence in New Orleans to prevent any repeat of the days-long crime wave and general chaos that followed Katrina.
