Sandy: Watch live video coverage and satellite tracking as United States braces for hurricane
Millions of people across the north-eastern United States were bracing for Hurricane Sandy as the superstorm picked up speed over the Atlantic.
It flooded shore towns and threatened to cripple Wall Street and New York City's subway system with a huge surge of corrosive seawater.
By midday, the storm was picking up speed and was expected to blow ashore in New Jersey or Delaware early in the evening, hours sooner than previously expected.
Forecasters warned it would combine with two other weather systems - a wintry storm from the west and cold air rushing in from the Arctic - to create an epic superstorm.
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From Washington to Boston, subways, buses, trains and schools were shut down and more than 7,000 flights grounded across the region of 50 million people.
Hundreds of thousands of people were under orders to move to higher ground to await the storm's fury.
President Barack Obama and Republican challenger Mitt Romney suspended their campaigning with just over a week to go before Election Day.
At the White House, Mr Obama made a direct appeal to those in harm's way: "Please listen to what your state and local officials are saying. When they tell you to evacuate, you need to evacuate. Don't delay, don't pause, don't question the instructions that are being given, because this is a powerful storm."
The storm washed away a section of the Atlantic City Boardwalk in New Jersey. Water was splashing over the seawalls at the southern tip of Manhattan.
A construction crane atop a luxury high-rise in midtown Manhattan collapsed in high winds and dangled precariously. Residents in surrounding buildings were ordered to move to lower floors and the streets below were cleared, but there were no immediate reports of injuries.
The major American stock exchanges closed for the day, the first unplanned shutdown since the September 11 attacks in 2001. Wall Street expected to remain closed on Tuesday. The United Nations cancelled all meetings at its New York headquarters.
Authorities warned that New York City and Long Island could get the worst of the storm surge: an 11ft (three metre) onslaught of seawater that could swamp lower Manhattan, flood the subways and damage the underground network of electrical and communications lines that are vital to the nation's financial capital.
About 16,000 New Yorkers lost power, mostly in the boroughs of Queens and Staten Island.
"Leave immediately. Conditions are deteriorating very rapidly, and the window for you getting out safely is closing," New York Mayor Michael Bloomberg told those in low-lying areas.
Defiant New Yorkers jogged, pushed buggies and took snapshots of churning New York Harbour, trying to salvage normal routines.
Without most stores and museums open, tourists were left to snap photos of the World Trade Centre site, Wall Street and Times Square in largely deserted streets.
As rain from the leading edges began to fall over the North-east yesterday, hundreds of thousands of people from Maryland to Connecticut were ordered to leave low-lying coastal areas, including 375,000 in lower Manhattan and other parts of New York City, 50,000 in Delaware and 30,000 in Atlantic City, New Jersey.
The storm washed away an old section of the world-famous Atlantic City Boardwalk and left most of the city's emptied-out streets under water. All 12 casinos in the city were closed, and some 30,000 people were under orders to evacuate.
Mr Obama declared emergencies in Massachusetts, Connecticut, Rhode Island, New York, New Jersey and Pennsylvania, authorising federal relief work to begin well ahead of time. He promised the government would "respond big and respond fast" after the storm hits.
New York shut down all train, bus and subway service last night. More than five million riders a day depend on the transit system. Boston, Philadelphia and Washington, DC, also shut down their transit systems. Authorities moved to close the Holland Tunnel, which connects New York and New Jersey, and a tunnel between Manhattan and Brooklyn.
Amtrak cancelled all train service cross the North-east until tomorrow.
Sandy, a Category 1 hurricane with top sustained winds of 90 mph (144 kph) was blamed for at least 69 deaths in the Caribbean before it began travelling northward, parallel to the Eastern Seaboard.
By afternoon, the storm was centred about 55 miles (15- kms) south-east of Cape May, New Jersey. It has speeded up to 28 mph (44 kph) and had begun the turn toward the coast that forecasters had feared. Forecasters say Sandy should reach the coast within three or five hours.
Sandy was expected to then collide with a wintry storm moving in from the west and cold air streaming down from the Arctic and cut across into Pennsylvania and travel up through New York state. Up to three feet (0.9 metres) of snow were forecast for mountainous parts of West Virginia.
New Jersey Governor Chris Christie was typically blunt: "Don't be stupid. Get out."
Coast Guard officials rescued 14 people and searched for two more who had abandoned a replica of the tall ship made famous in the film Mutiny on the Bounty after the vessel began taking on water off the North Carolina coast.
In Maryland, the storm caused significant damage to a large fishing pier in the beach resort of Ocean City. Governor Martin O'Malley says the fishing pier is now "half-gone."
Early voting was cancelled today in Maryland and Washington, DC.
Despite the dire warnings, some refused to budge.
Mark Vial pushed a buggy holding his two-year-old daughter Maziyar toward his apartment building in Battery Park City, an area in Lower Manhattan that was ordered evacuated.
"We're high up enough, so I'm not worried about flooding," said Via, 35. "There's plenty of food. We'll be ok.