The affected states are North Carolina, Virginia and Florida. According to the National Hurricane Center, windspeeds have diminished gradually. However, weather experts said the relentless rain still made the relief and rescue operation difficult.
President Barack Obama, who has declared State of Emergency in eight States, held two conference calls with his top national team. Cities in several States have declared curfew and police are not allowing people to come out on the streets.
The storm was classified as a hurricane when it swept through the Caribbean last week. Despite the downgrade to a tropical storm, it has still been destructive and disruptive. It is expected to hit Canada on Sunday night.
US Homeland Security Secretary Janet Napolitano said that while there was still a way to go with Irene, the “worst of the storm has passed”, adding that the precautions taken had “dramatically decreased” the threat to lives along the eastern US.
But National Hurricane Center director Bill Read warned that heavy rains meant there was still a major flooding risk to river systems, especially in New England.
According to BBC, some 370,000 people living in low-lying areas of New York City had been told to leave, and the city’s public transport system has been closed.
Ocean water has streamed into streets in New York’s Queens district, while streets in Brooklyn’s Coney Island were also under water. In Manhattan, water from New York Harbour lapped onto pavements in Battery Park, and about 1ft of water washed over the wall of the marina in front of the New York Mercantile Exchange.
Hours earlier, the then Hurricane Irene came ashore in New Jersey, about 100 miles (160km) to the south, where state Governor Chris Christie said he expected the cost of repairing damage to be “in the billions of dollars, if not in the tens of billions of dollars”.
The north-eastern seaboard is the most densely populated corridor in the US. More than 65 million people live in major cities from Washington DC in the south to Baltimore, Philadelphia, New York and Boston further north.