President Barack Obama has officially declared the floods caused by Tropical Storm Irene in North Carolina and New York a major disaster.
The move allows the two states to tap extra federal funds for relief efforts.
President Obama earlier signed emergency declarations for other states including Vermont.
About 40 people in the United States were killed by the storm, which also caused damage estimated at more than $US10 billion and forced a shutdown of New York City.
The BBC reports millions of people on the east coast are still without power.
The governors of New York, New Jersey and Connecticut requested disaster declarations on Tuesday.
In Paterson, New Jersey, the Passaic River crested 13ft above its banks - its highest level since 1903.
The National Weather Service has warned of moderate to major flooding on the Connecticut River, which crested at Middletown, Connecticut with a level of 15.4ft on Wednesday morning.
President Obama earlier declared a major disaster in the territory of Puerto Rico, which felt the early force of Irene as it moved through the Caribbean.