CHICAGO — A monster winter storm stretching from New Mexico to Maine laid down a sheet of ice on the Plains and lower Midwest Tuesday, turning to snow as it moved north, and experts said the worst was yet to come.
The storm, expected to hit as much as a third of the U.S. population, blanketed a wide swath with ice and sleet, creating dangerous travel conditions.
The Dallas-Fort Worth international airport closed for 2 1/2 hours Tuesday due to ice just as thousands of football fans began arriving in the city for the Super Bowl game on Sunday.
The top U.S. airlines United Continental, Delta Air Lines and American Airlines canceled more than 3,500 flights ahead of the storm.
More than 600 of those flights were at Chicago's O'Hare international airport, one of the world's busiest, the city's aviation department said.
In Washington, the federal government said that workers could take unscheduled leave or telecommute Tuesday because of the treacherous travel conditions.
Snow, sleet and freezing rain made for a messy, slippery commute in New York City, where forecasters said the wintry mix would last into Wednesday as the storm moved in from the Midwest.
"It's far from a picturesque scene. It's an icy, wet mess," said meteorologist John Davitt of local NY1 television.
The city's subways and buses were running but with delays and crowding due to weather-related equipment problems, authorities said.
Traffic was slowed on highways in and around New York City, and speed restrictions were imposed on the George Washington Bridge and the Tappan Zee Bridge, both of which span the Hudson River, due to the weather conditions, authorities said.
Wall Street financial markets were operating normally on Tuesday morning but officials were making plans for Wednesday.
In New England, light to moderate snow was already falling during the morning commute in Boston.
"Everyone should stay inside today and not drive," Missouri Gov. Jay Nixon said on local television.
Missouri and Oklahoma were among several states that declared a state of emergency even before the storm hit.
By the time the storm front reaches the upper Midwest later Tuesday, the National Weather Service said the ice and sleet could turn into one of the biggest blizzards in more than 40 years in Chicago, with as much as two feet of snow expected.
The snow is expected to be accompanied by high winds of more than 40 miles per hour and plunging temperatures.