A massive and deadly winter snowstorm blanketed the US Midwest on Thursday, grounding hundreds of planes and making roads and highways impassable as travelers gear up for the Christmas holiday.

The region's first big storm of the season dumped more than a foot (30 centimeters) of snow in parts of Wisconsin, Iowa and Minnesota overnight and more was expected as the powerful system moved slowly eastward.

Winds with gusts as high as 50 miles (80 kilometers) per hour felled trees and power lines, leaving tens of thousands of homes in the dark and cold.

Snow drifts reached as high as four feet in some places and visibility was down to near zero, the National Weather Service reported.

"Travel will be dangerous and potentially life threatening if you become stranded," the agency warned.

"Emergency services and rescues could be halted for a period of time during the height of the storm."

At least one person was killed in a 25-vehicle pileup after conditions got so bad on a major Iowa highway that people couldn't see the cars and big trucks that had slowed down or stopped ahead of them.

Roads across the state were blocked by jack-knifed trucks and stalled cars as officials pleaded with people to stay home.

"It's time to listen to warnings and get off the road," said Colonel David Garrison of the Iowa State Patrol.

A regional energy company said the storm had cut power to more than 40,000 households and businesses in Iowa, where nearly a foot of snow had fallen in the capital, Des Moines.

Wisconsin Governor Scott Walker issued a state of emergency and called up the National Guard ahead of the storm "to make sure Wisconsin is prepared for whatever this winter storm may bring."

Soldiers were prepositioned to help stranded motorists, but most were smart enough to stay home and the state highway patrol reported "no major crashes with only a few weather related vehicle run-offs."

Blizzard warnings were also issued in Nebraska, Missouri and Illinois and Michigan, Indiana and Ohio were bracing for the storm to hit the Great Lakes.

"Highways were a mess because it started as rain then changed to snow," Pat Slattery, a spokesman for the National Weather Service who works in Kansas City, Missouri, told AFP.

"I have 30 miles to get to work. It took me an hour and a half this morning."

The storm had also dumped more than two feet of snow in parts of the western US, including Washington state and Wyoming on Wednesday.

Airlines canceled more than 400 flights and passengers also encountered delays of up to four hours at Chicago's bustling O'Hare airport, one of the busiest in the world.

Rain made Chicago's runways and roads slick Thursday morning and heavy snow was anticipated to strike around 3:00 pm (2100 GMT) -- just in time to snarl the evening commute.

Another 124 flights were cancelled at the city's secondary airport, Midway.

Delays and cancelations could affect travel across the country, especially since many passengers need to change planes in Chicago or are reliant on aircraft that pass through the major aviation hub.

Flights through smaller airports in Iowa, Missouri, South Dakota, Wisconsin and Minnesota were also canceled on Thursday morning while a thunderstorm led to mass cancelations in Dallas.