CHICAGO (AP) — An army of snowplows was deployed to clear Chicago area roads after a winter storm left the region covered with a thick blanket of snow and the harsh conditions had left roads so slippery that authorities well south of the city were urging people not to drive unless it was absolutely necessary.

By mid-afternoon on Monday, as much as five inches of snow had fallen in some areas. The hundreds of city and state snowplows were trying to clear off roadways as police agencies were responding to dozens of traffic accidents.

The weather was affecting air travel as well. By mid-afternoon, Chicago's Department of Aviation reported that there had been nearly 150 flights canceled at the city's two major airports.