Snow and ice may be to blame for multiple crashes on Interstates 65 and 94 in Lake County, Indiana State Police said.
Minor injuries have been reported in some of the crashes, police said.
Much of I-65 between U.S. 30 and I-94 was moving slowly because of crashes near 61st Avenue and Ridge Road, according to the Indiana Department of Transportation's TrafficWise website.
Another crash on westbound I-94 near Kennedy Avenue resulted in a long backup.
Traffic also appeared to be moving slowly along Cline Avenue, with a crash near the Indiana Toll Road about 8:30 a.m.
Snow was possible Monday morning, with the most accumulation expected north of Interstate 90, according to the National Weather Service.
The snow was expected to taper off by Monday afternoon, but could return Monday night into Tuesday.