The severe weather has caused hundreds of accidents, and reached as far south as Texas - where there was a 50-vehicle motorway pile-up.
The storm, bringing ice and snow, has also felled trees and power lines. Dozens of flights have been cancelled.
More heavy snow has been forecast as the storms move into the Great Lakes region bordering Canada.
Multiple-vehicle pile-ups closed major highways in the central states over the weekend.
In Minnesota alone, there were more than 300 road accidents and three deaths.
Three other people died in accidents in Wyoming, and one each in Texas, Kansas and Wisconsin.
The fatality in Texas came in a chain-reaction pile-up on Interstate 40.
At least 16 people were taken to hospital, two with life-threatening injuries.
Many in the pile-up were holidaymakers, including families with small children not dressed for the weather, police said.
The BBC's Matthew Price in the US says Americans expect bad weather at this time of year and the country has the resources to cope.
But for some the fierce winter is making it a miserable Christmas, our correspondent adds.
Güncelleme Tarihi: 24 Aralık 2007, 07:24