Officials warn high water will continue to pose danger in wake of already deadly storm.
Millions are still without power and flooding remains a danger in the wake of Hurricane Irene.
At least 18 deaths have been blamed on the storm that raked the East Coast from North Carolina New England.
The storm surge flooded some Manhattan streets, but New York was spared the brunt of Irene's winds.
More than a foot of rain fell on less populated areas to the south.
Government officials say things could have been much worse if evacuation orders hadn't been followed.
"All in all, we are in pretty good shape because of the exhaustive steps we took to prepare for whatever came our way," said New York City Mayor Michael Bloomberg.
"This is not over," President Obama added during a statement from the White House Rose Garden. "Many Americans are still at risk of power outages and flooding which could get worse in the coming days as rivers swell past their banks."
At least 4 million homes and businesses are still without power, and preliminary estimates place the storm's cost at several billion dollars.
Torrential rains from now the remnants of Irene are still expected to trigger flooding far inland.
What's left of Irene is expected to continue dumping rain along Canada's eastern shore this evening and into Monday.