States of emergency were declared in New York and New Jersey, with officials urging residents to avoid unnecessary travel and dismiss employees early due to inundated roads and public transport disruptions.
Tragically, a child died in Mount Airy, Maryland, after being swept into a storm drain during the severe weather.
The National Weather Service attributed the intense rainfall to a slow-moving cold front carrying an unusual amount of moisture, affecting over 50 million people under flood watches.