BOSTON/NEW YORK (Reuters) - A blizzard swept across the northeastern United States, dropping more than 30cm of snow but falling short of more dire predictions that sent workers and students home, halted thousands of flights and prompted New York officials to ban cars from roads and shut down subway trains.

As day broke on Tuesday, the leaders of New York City, New York state and New Jersey began lifting travel bans imposed the night before, when forecasters warned of a potentially"historic" blizzard that could dump as much as 90cm of snow and paralyse the East Coast.

The National Weather Service lifted its blizzard warning for New York City, downgrading it to a winter storm warning, but cautioned that snow could fall off and on until midnight.

"We thought we were going to get something a lot bigger,"New York City Mayor Bill de Blasio told CNN. "We're going to quickly get back to normal here in New York City."

On New York's Long Island, Suffolk County Police said a teenager had died late on Monday when he crashed into a lamppost in the street where he was snow-tubing.

The New York Stock Exchange, owned by Intercontinental Exchange Inc, will run as usual, said spokesman Eric Ryan. Nasdaq OMX Group, and BATS Global Markets also expected to stay open for normal operating hours on Tuesday.

In Washington, federal offices and city public schools were scheduled to open two hours late, to allow additional travel time.

High winds and heavy snow were set to persist throughout the day, with another foot forecast to fall in parts of Boston. Wind-driven seas caused flooding along some low-lying roadways in coastal Massachusetts, state police said.

CONNECTICUT, MASSACHUSETTS AMONG HARDEST HIT

Some of the heaviest snowfall was recorded in parts of Connecticut and Massachusetts, while New York City's Central Park saw just 15cm, less than a quarter of the"historic" snowfall that some meteorologists had predicted.

"When you hear the word 'crippling' and you look out your window this morning, it is not there," said John Davitt, a meteorologist on New York's NY1 news channel.

Travel was still snarled, with more than 4,500 flights cancelled at US airports, according to FlightAware.com, and no trains or buses in New York, Boston or New Jersey.

Fewer Massachusetts residents and businesses lost power than was expected, said Governor Charlie Baker, saying that temperatures well below freezing had resulted in light snow. High winds could yet result in additional outages, he said.

"We'll continue to see high winds throughout the course of the day," Baker told reporters Tuesday. "People should spend the morning digging out, cleaning up."

The more dire forecasts of snow had prompted governors in eight East Coast states to declare states of emergency and the storm affected up to 60 million people in nearly a dozen states.

Residents largely obeyed orders to stay off roadways and broadcasters in New York and Boston showed roads largely free of cars early on Tuesday.

Sustained winds in the area might hit 64 kph, though gusts as high as 126 kph were recorded on the island of Nantucket, off Massachusetts.

Massachusetts' Pilgrim nuclear power plant powered down on Tuesday after lines allowing it to transmit electricity went down, officials said.

"SNOWMAGEDDON" ON SOCIAL MEDIA

Stuck at home, many turned to social media to give voice to their frustration, adopting such storm-related hashtags as #blizzardof2015, #Snowmageddon2015 and #Snowpocalypse.

"Across NE, millions are panicked they may lose internet and have to talk to their families. Trying hard to remember names. #Snowmageddon2015," tweeted Stuart Stevens.

The United Nations headquarters gave itself a day off on Tuesday. East Coast schools, including New York City - the nation's largest public school system, serving 1 million students - shut down. Universities, including Harvard and the Massachusetts Institute of Technology, canceled classes.

The last time bad weather closed the stock markets was in October 2012 when superstorm Sandy ravaged the East Coast with flooding, punishing winds and widespread power outages.

The brutal weather paralyzed the New York City metropolitan area, with a shutdown of all subway, bus and commuter rail services on Metro-North Railroad and Long Island Rail Road. It was the first time the city subway had been halted due to snow.

Coastal flood warnings were issued from Delaware to Maine, and National Weather Service officials in Boston reported early on Tuesday that waves just a few miles outside of Boston Harbor approached 6m.

Amtrak suspended rail services between New York and Boston, and into New York State, Vermont, Massachusetts and Maine.

The biggest snowfall on record in New York City was during the storm of Feb 11-12, 2006, when 68cm fell, according to the city's Office of Emergency Management.

For a graphic on snowstorms: http://link.reuters.com/wur83w