Officials in the states of Connecticut, New York, New Jersey, Maryland, Pennsylvania, West Virginia and North Carolina all reported deaths on Tuesday from the massive storm system, while Toronto police said a Canadian woman was killed by flying debris.
Sandy had already killed at least 67 people – including a US national in Puerto Rico – as it swept through the Caribbean over the past few days, meaning the overall toll from the storm is now approaching 100.
New York Governor Andrew Cuomo reported 15 storm-related deaths at a news briefing, including at least 10 killed when Sandy struck New York City.
"Tragically we expect that number to go up," New York mayor Michael Bloomberg warned.
Three people died in New Jersey, including two parents who were killed when a falling tree crushed their car, sparing their children aged 11 and 14 who were inside with them, Governor Chris Christie said.
Christie added that rescue operations were still under way, with three separate teams deployed in Atlantic City, the coastal casino town near where the storm made landfall at 0000 GMT on Tuesday.
Another four people were killed in Pennsylvania, including one killed from a falling tree and another when a house collapsed, emergency management officials told AFP.
Connecticut Governor Dan Malloy on Tuesday said two people had been killed in his state, including a firefighter, and two others were missing.
Elsewhere along the East Coast, a woman on board a replica of the HMS Bounty was recovered from the sea and later died at hospital. The captain was still missing on Tuesday after the tall ship went down off the Carolinas.
A vehicle driver and his passenger were killed in the Virginia state capital of Richmond in the pre-dawn hours of Tuesday, city police said in a statement. The driver lost control of his car in heavy rain and slammed into a light pole, then struck a tree, city police said.
A woman in Maryland died after her vehicle hydroplaned into a tree, officials said. And in West Virginia, a 48-year-old woman was killed when her car collided with a cement truck, while driving through heavy snow caused by the storm, a local official said.
The National Hurricane Centre said Sandy had weakened early on Tuesday as it moved inland, but could still generate gale-force winds and flooding along the eastern seaboard.
US authorities had warned the threat to life and property was "unprecedented" and ordered hundreds of thousands of residents from New England to North Carolina to evacuate their homes and seek shelter.
Falling trees dragged down power cables, plunging millions of homes into darkness, while storm warnings cut rail links and marooned tens of thousands of travelers at airports across the region.
Disaster estimating firm Eqecat forecast that the massive storm would affect more than 60-million Americans, a fifth of the population, and cause up to $20-billion in damage.
Meanwhile, the New York Stock Exchange and the Nasdaq exchange announced they would reopen on Wednesday after Hurricane Sandy forced a two-day shutdown, the markets' first closure since the 9/11 attacks of 2001.
"We are pleased to be able to return to normal trading tomorrow," said NYSE Euronext chief executive Duncan Niederauer. "Our building and systems were not damaged and our people have been working diligently to ensure that we have a smooth opening tomorrow."
Niederauer said trading will start as usual at 9.30 am, with the NYSE Euronext building and trading floor "fully operational" despite the flooding and power outages that have shut down much of the country's financial capital New York.
Nasdaq OMX, which operates the fully electronic Nasdaq exchange and other futures and options markets, said they would also reopen at normal hours on Wednesday.
US financial markets were almost all closed Monday and Tuesday as the mega-storm bore down on the US East Coast, shutting down New York, Philadelphia, Baltimore and Washington.
It was the first closure of the markets since 9/11 and the first weather-related closure since September 1985 when Hurricane Gloria closed the NYSE for one day. – Sapa-AFP