Flooding killed at least nine people, swept away cars, submerged subway lines and grounded flights in New York and New Jersey as the remnants of Hurricane Ida brought torrential rains to the area.
At least five flash flood emergencies were issued on Wednesday evening by the National Weather Service, stretching from west of Philadelphia through northern New Jersey.
All New Jersey Transit rail services apart from the Atlantic City Rail Line were suspended, the service said on its website.
Tornadoes spawned by the storm ripped through parts of Pennsylvania and New Jersey, images on social media showed.
New Jersey's Newark Liberty Airport said on Twitter it was experiencing "severe flooding." It said it resumed "limited flight operations" close to midnight after all flight activity was suspended late on Wednesday.
More than 200,000 electricity customers were without power early on Thursday in five northeastern states that got most of the rains overnight, mostly in Pennsylvania and New Jersey, according to PowerOutage.US, which gathers data from utility companies. There were also outages in New York, Connecticut and Massachusetts, it said.