Hurricane Sandy is set to bring much of the East Coast of the United States, including New York and Washington, to a virtual standstill in the next few days.
After laying waste to parts of the Caribbean, where it claimed 66 lives - most of them in Cuba and Haiti - Sandy is predicted to come crashing ashore in New Jersey and Delaware late on Monday or early on Tuesday (local time).
Flights in and out of New York, Washington, Boston and Philadelphia have been cancelled, while New York's subway is closed and millions of children are being kept home from school.
In New York, authorities ordered the evacuation of 375,000 people from low-lying coastal areas, while Delaware has ordered a mandatory evacuation of 50,000 people.
Governors have declared states of emergency in Connecticut, Delaware, Maryland, Massachusetts, New Jersey, New York, North Carolina, Pennsylvania, Vermont, Virginia and the capital Washington, AFP reports.
Residents from Washington to New York to Boston queued for emergency provisions, including bottled water and batteries in long lines that stretched out the doors of supermarkets.
Forecasters warn the massive storm is far larger and more dangerous than last year's devastating Hurricane Irene that claimed 47 lives and caused an estimated $US15 billion in damage. The National Hurricane Centre says everywhere from South Carolina to southern Canada could be affected by Sandy.
The New York Stock Exchange said its trading floor would be closed on Monday, but electronic transactions would still be possible.
The storm has affected the US presidential race, with President Barack Obama and Republican governor Mitt Romney pulling out of rallies in must-win states. The White House says Mr Obama will not attend a rally in Ohio and will return to Washington to monitor the situation.
The hurricane could disrupt early voting before the election on 6 November.