A fearsome storm spread a smothering shroud of white over nearly half the US on Wednesday, snarling transportation, burying parts of the Midwest under 2 feet (60 centimeters) 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 (51 centimeters) 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 (50-centimeter) 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 (a meter) 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.
Although skies were beginning to clear by mid afternoon over much of the country's midsection, the storm promised to leave a blast of bitter cold in its wake. Overnight temperatures in northern parts of the Midwest were expected to fall to minus 5 to minus 20 Fahrenheit (about minus 20 Celsius), with wind chills dropping to 20 to 30 below zero (about minus 30C).
The system was blamed for at least 12 deaths, 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 across the US, 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 caused several structures to collapse, including a gas station canopy on Long Island and an airplane hangar near Boston. In at least two places, workers heard the structures beginning to crack and narrowly escaped.
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. Some motorists came away angry, frustrated that the city didn't close the crucial thoroughfare earlier. Others were mad at themselves for going out during the storm or not using another route.
At dusk Wednesday, more than 200 cars remained on the drive, and city workers planned to work through the night to remove them. But it wasn't clear whether the job would be done in time for the morning rush.
Elsewhere, utility crews raced to restore power to tens of thousands of homes and businesses in Ohio, New Jersey and Pennsylvania, where freezing rain and ice brought down electrical lines. Rolling blackouts were implemented across Texas, due to high demand during a rare ice storm.
In Canada, heavy snow canceled about a quarter of the 1,200 scheduled flights at Toronto's international airport, closed schools, and caused dangerous driving conditions due to drifting snow.
The storm derived its power from the collision of cold air sweeping down from Canada and warm, moist air coming up from the south. The contrasts were most dramatic in Texas earlier in the week, when one part of the state reported temperatures below freezing and another part had temperatures in the 70s around (20C), with near tropical humidity.
Louis Uccellini, director of the government's National Centers for Environmental Prediction, said the storm also drew strength from the La Nina condition currently affecting the tropical Pacific Ocean.
La Nina is a periodic cooling of the surface temperatures of the tropical Pacific Ocean, the opposite of the better known El Nino warming. Both can have significant impacts on weather around the world by changing the movement of winds and high and low pressure systems.