The snow will continue overnight, and by Wednesday morning there could be up to 12 inches on the ground.
Northwest Indiana and Michigan will be getting the worst of the snowfall in the morning hours.
Chicago's Snow Command will keep its full main fleet of 275 trucks out overnight in an effort to keep the main thoroughfares cleared. Tuesday was only the second time the full fleet has been deployed all year.
Concerns over visibility prompted officials at the Illinois Department of Transportation to ask motorists to use public transportation instead of driving themselves.
"We do expect tomorrow morning to be very slow moving," IDOT spokeswoman Marisa Kollias said Tuesday. "I don't think the visibility will change all that much from now."
The snowfall and plows made for messy Tuesday commutes, and the traffic backups affected snow plows as well.
The storm caused at least one fatality: a Rogers Park woman was struck and killed by a snow-plow equipped truck as the driver reversed into a driveway Tuesday afternoon.
Chicago Transit Authority officials, already anticipating long lines for buses and trains, advise riders to get to their stop up to 45 minutes early.
Air travelers might want to check on their flight before they leave the house. More than 600 flights in and out of Chicago' O'Hare Airport have been cancelled due to inclement weather.
All flights in and out of O'Hare are reporting delays of at least 90 minutes.
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