From North Carolina to Maine, communities cleaned up and took stock of the uneven and hard-to-predict costs of a storm that spared the nation's biggest city a nightmare scenario, only to deliver a historic wallop to towns well inland.

In New York City, where people had braced for a disaster-movie scene of water swirling around skyscrapers, the subways and buses were up and running again in time for the Monday morning commute. And to the surprise of many New Yorkers, things went pretty smoothly.

But to the north, landlocked Vermont contended with what its governor called the worst flooding in a century.

Streams also raged out of control in rural, upstate New York.

In many cases, the moment of maximum danger arrived well after the storm had passed, as rainwater made its way into rivers and streams and turned them into torrents. Irene dumped up to 11 inches (28 centimetres) of rain on Vermont and more than 13 inches (33 centimetres) in parts of New York.

"We were expecting heavy rains," said Bobbi-Jean Jeun of Clarksville, a hamlet near Albany, New York. "We were expecting flooding. We weren't expecting devastation. It looks like somebody set a bomb off."

Irene killed at least five people in the Dominican Republic and Haiti. The first known casualty was a woman who died trying to cross a swollen river in the US territory of Puerto Rico.

The death toll for 11 eastern US states had stood at 21 as of Sunday night, then rose sharply to at least 38 as bodies were pulled from floodwaters and people were struck by falling trees or electrocuted by downed power lines.

A driver was missing after a road collapsed and swallowed two cars about 62 miles (100 kilometres) northeast of Montreal.

The tally of Irene's destruction mounted, too. An apparently vacant home exploded in an evacuated, flooded area in Pompton Lakes, New Jersey, early Monday, and firefighters had to battle the flames from a boat. In Albany, New York, a suburb of Guilderland, police rescued two people Monday after their car was swept away. Rescuers found them three hours later, clinging to trees along the swollen creek.

"It's going to take time to recover from a storm of this magnitude," President Barack Obama warned as he promised the government would do everything in its power to help people get back on their feet.

For many people, the aftermath could prove more painful than the storm itself.

In North Carolina, where Irene blew ashore along the Outer Banks on Saturday before heading for New York and New England, 1,000 people were still in emergency shelters, awaiting word on their homes.

At the same time, nearly 5 million homes and businesses in a dozen states were still without electricity, and utilities warned it might be a week or more before some people got their power back.

"Once the refrigerator gets warm, my insulin goes bad. I could go into diabetic shock. It's kind of scary because we don't know how long it's going to be out for," said Patricia Dillon, a partially paralysed resident of a home for the disabled in Milford, Connecticut, where the electricity was out and a generator failed. Her voice cracking, she added: "I'm very tired, stressed out, aggravated, scared."

As the storm continued its march into eastern Canada, Irene brought strong winds, gusting near 55 miles (90 kilometres) an hour, to parts of southern New Brunswick, northern and mainland Nova Scotia and Prince Edward Island.

Environment Canada said the strongest winds were felt just east of Quebec City on Ile d'Orleans, where gusts of 70 miles (113 kilometres) an hour were reported.

The impact of storm left about 165,000 power customers in Quebec without electricity Monday, while tens of thousands more in New Brunswick and Nova Scotia were also waiting for the lights to come back on.

Up and down the Eastern Seaboard, commuters and vacationers found their travel plans scrambled.

Airlines warned it would be days before the thousands of passengers stranded by Irene find their way home. Some Amtrak passenger service in the Northeast was suspended.

Commuter trains between New Jersey and New York City were not running. Trains between the city and its northern suburbs were also disrupted.

In Vermont, the state's emergency management headquarters stood empty, evacuated because of river flooding from Irene's heavy rains. Rescuers used a boat and bucket loaders to pluck seven people from a swamped mobile home park in Lyndonville.

Flood waters also shut down the Vermont Emergency Management headquarters, the Vermont State Hospital and other state agency offices. About 50 patients were moved from the psychiatric hospital to other facilities.

In upstate New York, authorities were closely watching major dams holding back drinking water reservoirs.

Early estimates put Irene's damage at $7 billion to $10 billion, much smaller than the impact of monster storms such as Hurricane Katrina, which did more than $100 billion in damage. Irene's effects are small compared to the overall US economy, which produces about $14 trillion of goods and services every year.

Many people were surprised by the destruction that Hurricane Irene wrought in communities far inland. But National Weather Service records show that 59 per cent of the deaths attributed to hurricanes since the 1970s have been from freshwater flooding.

As for why the flooding was so bad this time, Shaun Tanner, a meteorologist with the forecasting service Weather Underground, noted that August had been unusually wet, and Irene's sheer size meant huge amounts of rain were dumped over a very large area.

"More attention should have been paid to the torrential rain that Irene was going to dump not only on coastal areas, but also inland. That was clear several days ahead of time," Tanner said.