Dozens of cars spun out on area highways overnight as snow and cold winds glazed area bridges and highways.
Most of the crashes did not result in serious injuries, police said.
Close to 20 cars crashed on toll roads, Illinois State Police Sgt. Anton Manuel said.
"The weather just took a turn for the worst before our units could get the roads salted," he said. "Seems like every vehicle that came through the area spun out."
Additional crashes numbering in the dozens were reported in the Chicago District of the Illinois State Police, which covers Interstates 90, 94, 57, 55, and 290.
The most serious overnight crash appears to have happened on Interstate 290 in Addison, where a 61-year-old man sustained serious injuries and was taken to Alexian Brothers Hospital. The 33-year-old driver of the car was also injured, though his wounds were less serious, police said.
The occupants of the other car involved in that crash are OK, police said.
The accidents happened in a span of about 3 hours, Manuel said. The roads have since been salted and conditions have improved, he said.