Eleven people have been killed in series of road traffic accidents – the worst of which caused a pile-up of more than 50 vehicles including several tractor-trailer rigs in Texas.

One driver was killed in that accident and at least three people in Minnesota, three in Wyoming, three in Wisconsin and one person in Kansas were killed in traffic accidents that authorities blamed on the storm.

The weather was beginning to ease today but police warned against non-essential travel describing the road surfaces as like ice-rinks.

"The roads aren't quite as ice-covered but we're still telling people not to drive unless they have to," said Tim Elve of the Dane County Sheriff's Office in Wisconsin. "The interstate is still slick and the rural roads are really bad."

Winter storm warnings are set to be relaxed later today but roads in Minnesota, Wisconsin and Michigan are still affected.

Authorities issued urgent pleas for travellers to stay at home yesterday but officials now fear that a surge of motorists would set off this morning to reach their destinations in time for Christmas.

"I know it's the holidays but we hope people use some common sense when travelling," said Chad Breuer of the Grant County Sheriff's Department in southwest Wisconsin. "There are a lot of people saying, 'I'll just leave that much earlier' but still, the roads are not favourable for travelling."

Winds were recorded blowing as fast as 88 mph over Lake Michigan, with gusts of 50 to 68 mph across the Chicago region, according to the US National Weather Service.

The wind forced airlines to cancel more than 300 flights at Chicago's O'Hare International Airport yesterday. Chicago municipal officials said the wind had knocked out nearly 170 traffic signals and there were more than 500 reports of fallen trees.

More than 11,000 homes and businesses were without power over the weekend in Wisconsin because of the freezing rain, ice, gusty wind and heavy snow. Michigan utility companies reported that some 60,000 customers were still without power by Sunday night and in Illinois about 15,000 households were still in the dark.