A massive winter storm pounding the northern United States grounded over 1,200 flights, closed hundreds of schools and made roadways and highways impassible Tuesday.

More than a dozen states from Minnesota to Virginia were in the path of the huge storm which had already dumped as much as two feet (60 centimeters) of snow in Montana and 15 inches (38 centimeters) in North Dakota.

Emergency crews recovered the body of a truck driver whose rig slipped off a Wisconsin highway and ended up in a river and were searching for his passenger Tuesday, WQOW news reported.

Minnesota's highway patrol responded to 122 crashes and 112 vehicles that had spun off the road between 5 am and 10:40 am, but luckily there were no fatalities and just 16 injuries, KARE news reported.

The heavily populated Chicago area was expected to get as much of an inch (2.5 centimeters) of snow an hour during the evening rush, the National Weather Service said.

Hundreds of plows were working the Windy City's roads and freeways but with up to 10 inches (25 centimeters) of snow expected, there was no way they could keep up.

"Significant amounts of snow are forecast that will make travel dangerous," the weather service warned. "Consider only traveling if in an emergency."

More than 800 flights were grounded at Chicago's O'Hare airport -- a major hub -- while another 240 were cancelled at Chicago Midway. Over 100 flights were cancelled in Minneapolis, Minnesota, according to FlightAware.

The storm was expected to hit the nation's capitol late Tuesday or early Wednesday, and some Congressional meetings were already being cancelled in Washington.

"We think the system will develop into a more powerful storm as it passes into the mid Atlantic states," Dan Petersen, a meteorologist with the National Weather Service, told AFP.

"This could be a heavy, wet snow so there could be tree branches and power lines brought down."

The storm will merge with a second system over the Appalachians Tuesday night and also pull moisture off the Atlantic.

Washington will get a slushy mix of rain and about four to eight inches (10 to 20 centimeters) of snow, which could create gridlock if it ends up hitting during the evening or morning commutes.

The comparatively balmy city's residents are not as well prepared for driving on snow, slush and ice as those in northern areas like Chicago and New England, said Petersen, who works at the weather service headquarters in Washington.

"People forget their winter weather driving skills," Petersen told AFP.

"We've had people get frustrated and just leave their cars on the road, creating an obstacle."