In Maryland, at least 100 feet of a fishing pier at the beach resort of Ocean City was destroyed, and Gov. Martin O'Malley said there would be devastating flooding from the swollen Chesapeake Bay.
"There will be people who die and are killed in this storm," he said.
At least half a million people had been ordered to evacuate, including 375,000 from low-lying parts of New York City, and by the afternoon authorities were warning that it could be too late for people who had not left already.
Millions of people stayed home from work. Sheila Gladden evacuated her home in Philadelphia's flood-prone Eastwick neighborhood, which took on 5½ feet of water during Hurricane Floyd in 1999, and headed for a hotel.
"I'm not going through this again," she said.
Those who stayed behind had few ways to get out. New York's subways, which serve 5 million people a day, were shut down. The Holland Tunnel connecting New York to New Jersey was closed, as was a tunnel between Brooklyn and Manhattan, and the city planned to shut down the Brooklyn Bridge, the George Washington, the Verrazano-Narrows and several other spans because of high winds.
Stock and bond markets were closed Monday and Tuesday, the first shutdown since the days after the Sept. 11 attacks in 2001 and the first two-day closing of the stock market because of weather since a blizzard in 1888. The New York Stock Exchange is inside the mandatory evacuation zone in lower Manhattan, blocks from New York Harbor.
If the storm reaches the higher estimate of $20 billion in damage, that would put it ahead of Hurricane Irene, which raked the Northeast in August 2011 and caused $16 billion in damage. Hurricane Katrina, which killed 1,200 people, cost $108 billion.
McClam reported from New York. AP Science Writer Seth Borenstein contributed to this report from Washington. Associated Press writers Allen G. Breed in Raleigh, N.C.; David Porter in Pompton Lakes, N.J.; Wayne Parry in Point Pleasant Beach, N.J.; and David Dishneau in Delaware also contributed.