A historic snowstorm blasted its way through the Northeast Monday, threatening to wreak havoc in seven states, with thousands of flight cancellations, school closings and the prospects of up to 3 feet of snow and hurricane-force winds expected to impact over 40 million people.

New Jersey, Massachusetts and Connecticut issued statewide road travel bans ahead of the brunt of the blizzard's onslaught, dubbed Winter Storm Juno.

"We encourage citizens to stay in place during the duration of the storm," said Conn. Gov. Dannel Malloy. "We believe this will be a long duration cleanup."

"This is clearly going to be a really big deal,'' said Mass. Gov Charlie Baker, who predicted the blizzard would be a "top-five historic storm."

At least 7,500 flights into and out of the region were canceled through Wednesday. Amtrak service was suspended between New York and Boston for Tuesday, while other regional routes were to operate on reduced schedules. Strong winds had ConEd and other utility companies bracing for widespread power outages, with emergency repairs crews from Michigan and other areas already en route.

New York City took the rare step of banning all forms of travel due to the storm, grinding the city that never sleeps to a halt. Boston took similar measures. A blizzard warning was issued for both metropolitan areas.

"It's dangerous out there now. It's only going to become more dangerous,'' New York Gov. Andrew Cuomo said Monday evening as he announced a total ban on travel on any road after 11 p.m. in 13 counties.

Central Park recorded more than 4 inches of snow by 7 p.m., when there was a lull in the snowfall. But the city was taking no chances.

"This will most likely be one of the largest blizzards in the history of New York City,'' said Mayor Bill de Blasio.

The treacherous, 24-hour-plus snow odyssey was expected to be most severe late Monday and deep into Tuesday. AccuWeather senior meteorologist Tom Kines said Philadelphia, New York City and much of New England could see 1-2 feet of snow. Parts of central Massachusetts and central Connecticut could be hit by 2 to 3 feet, he said.

Wind gusts could reach 40-55 mph in many areas, with 60 mph or more possible along the coast, Kines said.

"Travel will be impossible. Forget about it on Tuesday," Kines told USA TODAY. "The sun will come out Wednesday, and they all can start digging out."

New Jersey Gov. Chris Christie warned residents to stay inside.

"You should only go out in case of an absolute emergency or necessity," Christie said. "We do not need people on the roadways. It makes it much more difficult to do our jobs. We would like to make Wednesday productive for everybody, and the only way for us to make Wednesday productive is for you to give us the opportunity to do our job on Tuesday and (Monday) evening."

New Jersey state climatologist David Robinson said the storm could challenge the state record of 34 inches that dates back to February 1899.

New York City's Department of Homeless Services activated its "Code Blue" winter weather emergency procedure, making it possible for homeless people to stay at any city shelter, regardless of which one they're assigned to. The department said it would double the number of "outreach vans" on the streets overnight through Wednesday and said another 10 vans will be out finding homeless New Yorkers along the city's subway system.

The weather service blizzard warning was bleak, foreseeing "life-threatening conditions and extremely dangerous travel due to heavy snowfall and strong winds. With whiteout conditions many roads may become impassable, strong winds may down power lines and tree limbs."

The weather service labels a snowstorm a blizzard when winds reach 35 mph and blowing snow reduces visibility to less than a quarter of a mile.

"It will be like a tidal wave of snow into New England tonight into Tuesday," tweeted AccuWeather meteorologist Henry Margusity.

The New York City travel ban is not unprecedented. Travel bans were in place during blizzards of 2006, 1996, 1983 and 1947, says Sam Schwartz, a former city transportation commissioner and now a traffic consultant. He knows about the Dec. 26, 1947 storm -- he was born three days before it struck and was taken home by sled.

A similar ban was in place in parts of lower Manhattan after the Sept. 11, 2001 terror attacks. After Superstorm Sandy in 2012, the city banned all traffic except high-occupancy or emergency vehicles from bridges and tunnel crossings into the city for several days.

On an average day about 2 million motor vehicles use New York City streets.

In Brooklyn, N.Y., snow quickly covered homes, cars and sidewalks Monday. Streets were filled with people clearing off their vehicles, throwing down snow-melting salt, and chatting about the coming storm.

Rafael Aquino, 62, has lived in Brooklyn all his life and said he isn't surprised that a large storm is heading his way.

"It's inevitable," he said, noting that the city had enjoyed a relatively mild winter so far. "It was just too nice. We had too much good weather."

Folks were getting ready in various ways for the storm: Drizly, an alcohol delivery app, reported that deliveries in Boston and New York City were up 477% over a typical Monday.

The Metropolitan Transit Authority said it hoped to keep city buses running as long as possible, warning that "depending on road conditions, service may be curtailed as the day progresses."

In Philadelphia, where forecasts ranged from 8 to 18 inches of snow, schools closed at noon Monday. The National Guard activated 150 people in the area.

Pennsylvania Gov. Tom Wolf promised that more than 2,500 trucks would tackle the state's roads. T

At the southern end of the storm, the Washington, D.C. area was not expected to get more than a couple inches of snow.

The storm's impacts could last long after it heads offshore: Power outages, snow-packed roads and school closures may last for days after the blizzard, AccuWeather meteorologist Brian Lada said.

Coastal New England should see some of the worst impacts from the storm's pounding surf and near-hurricane force winds, including severe beach erosion and flooding of vulnerable shore roads and homes: "This storm has enough intensity that it could cause new inlets to be formed along barrier beaches," the weather service in Boston warned.