More cold, snow, ice, wintry mix for much of U.S.

A wide swath of the country shivered in freezing, record-breaking temperatures, while other areas saw more winter precipitation Tuesday.

A mix of snow, sleet, rain and freezing rain hit parts of the southern Plains and the South, where school districts in more than a half-dozen states from Texas eastward canceled or delayed classes.

Meanwhile, the East Coast endured colder-than-usual weather.

Temperatures were well below average in many spots, even far below zero.

The wintry weather showed no sign of letting up: Especially in the South, people braced for more storms later this week.

Here's a look at what's happening:

Chain-reaction crash

A man was seriously injured after he got out of his car on a Michigan bridge and was struck by a vehicle in a chain-reaction crash, officials said.

The 11-vehicle wreck happened around 9:30 a.m., executive secretary Bob Sweeney of the Mackinac Bridge Authority said.

Winds up to 50 mph whipped snow off the frozen Straits of Mackinac, making visibility poor, Sweeney said.

A man got out of his car to switch places with his wife and was hit. Then a number of other vehicles ran into each other, he said.

The injured motorist was taken to a hospital, but his condition was unknown, Sweeney said.

The 5-mile-long bridge was closed until about 2:20 p.m.

Salt shortage

As snow and frigid temperatures continue in Ohio, communities in parts of the state are running short on road salt, city officials said.

Some cities have waited weeks for hundreds of tons of ordered salt, the Northeast Ohio Media Group reported.

The region has recorded nearly 60 inches of snow since November. Lower-than average temperatures have made snow harder to melt and roads more difficult to clear.

"We have enough to last this next week, but if it keeps consistently snowing it's going to be difficult," Middleburg Heights Service Director Jim Herron said.

Snowball fight

At Duke University, psychology professor Amir Rezvani brought his class outside for an impromptu snowball fight near the traffic circle that surrounds the statue of Washington Duke. More than two dozen students giggled and bent over to grab handfuls of snow and pelt one another.

"I asked them to come out for 10 minutes," Rezvani said before bending over and balling up some snow.

Mary Gabrielle Thomas, a freshman from Boston, said the "snow's not very impressive." But she admitted the snowball fight was wonderful.

Hikers beware

At the Top of Georgia Hostel & Hiking Center, a shelter for hikers on the Appalachian Trail, the branches of pine trees were dipping low with the weight of about 4 inches of snow, proprietor Bob Gabrielsen said Tuesday morning.

About 16 hikers spent the night Monday, Gabrielsen said, and all of them hiked out Tuesday morning on the trail, which was transformed into a bright white snowscape in the north Georgia mountains east of Hiawassee. This time of year, some hikers camp on the trail itself.

Gabrielsen warned that inexperienced hikers could find themselves in trouble because weather forecasts aren't always accurate, cellphone coverage can be spotty or nonexistent, and roads can be several miles away.

Some people think hiking the Appalachian Trail "is like the Pirates of the Caribbean ride where you can get off when you want to -- and you can't necessarily do that," Gabrielsen said.