Hundreds of cars are seen stranded Wednesday on Lake Shore Drive in Chicago. A winter blizzard of historic proportions wobbled an otherwise snow-tough Chicago, stranding hundreds of drivers for up to 12 hours overnight on the city’s showcase lakeshore thoroughfare and giving many city schoolchildren their first-ever snow day.

A fearsome storm spread a smothering shroud of white over nearly half the nation Wednesday, snarling transportation from Oklahoma to New England, burying parts of the Midwest under 2 feet of snow and laying down dangerously heavy ice in the Northeast that was too much for some buildings to bear.

Tens of millions of people stayed home. The hardy few who ventured out faced howling winds that turned snowflakes into face-stinging needles. Chicago’s 20.2 inches of snow was the city’s third-largest amount on record. In New York’s Central Park, the pathways resembled skating rinks.

The storm that resulted from two clashing air masses was, if not unprecedented, extraordinarily rare for its size and ferocious strength.

“A storm that produces a swath of 20-inch snow is really something we’d see once every 50 years — maybe,” National Weather Service meteorologist Thomas Spriggs said.

Across the storm’s path, lonely commuters struggled against drifts 3 and 4 feet deep in eerily silent streets, some of which had not seen a plow’s blade since the snow started a day earlier. Parkas and ski goggles normally reserved for the slopes became essential for getting to work.

“This is probably the most snow I’ve seen in the last 34 years,” joked 34-year-old Chicagoan Michael George. “I saw some people cross-country skiing on my way to the train. It was pretty wild.”

Although skies were beginning to clear by mid-afternoon over much of the nation’s midsection, the storm promised to leave a blast of bitter cold in its wake. Overnight temperatures in the upper Midwest were expected to fall to minus 5 to minus 20, with wind chills as low as minus 30.

The system was blamed for the deaths of at least a dozen people, including a homeless man who burned to death on New York’s Long Island as he tried to light cans of cooking fuel and a woman in Oklahoma City who was killed while being pulled behind a truck on a sled that hit a guard rail.

Airport operations slowed to a crawl nationwide, and flight cancellations reached 13,000 for the week, making this system the most disruptive so far this winter. A massive post-Christmas blizzard led to about 10,000 cancellations.

In the winter-weary Northeast, thick ice collapsed several structures, including a gas station canopy on Long Island and an airplane hangar and garages near Boston. In at least two places, workers heard the structures beginning to crack and narrowly escaped.

In Middletown, Conn., the entire third floor of a building failed, littering the street with bricks and snapping two trees. Acting Fire Marshal Al Santostefano said two workers fled when they heard a cracking sound.

“It’s like a bomb scene,” Santostefano said. “Thank God they left the building when they did.”

More than a half-dozen states began digging out from up to a foot of snow that made roads treacherous and left hundreds of thousands of homes without power.

Chicago public schools canceled classes for a second straight day. And the city’s iconic Lake Shore Drive remained shut down, nearly a day after drivers abandoned hundreds of snowbound vehicles.

The famous freeway appeared as if rush hour had been stopped in time, with three lanes of cars cluttering the pavement amid snow drifts that stood as high as the windshields. Bulldozers worked to clear the snow from around the cars, which were then plucked out by tow trucks one by one.

As the storm built to full strength Tuesday evening, 26-year-old Lindsey Wilson sat for hours on a stranded city bus. She eventually joined other passengers who tried to walk home. She made it about 100 feet before she couldn’t see anything around her, including the bus she’d just left.

Fearing she would be swallowed by mounting snow drifts, Wilson turned back and spent the night on the bus.

“I thought if I fall over, what would happen if I got buried under a pile of snow?” she said.

Some motorists came away angry, frustrated that city didn’t close the crucial thoroughfare earlier. Others were mad at themselves for going out during the storm or not using another route.