Heading South on I-94, you will need toll money.
These directions are directly after passing Six Flags Theme Park:

1: Take the I-94 SOUTH/TRI-STATE towards INDIANA. (Portions toll). 25.6 miles (41.2 km)

2: Take the US-41 SOUTH/SKOKIE RD exit, exit number 34A. 0.4 miles (0.7 km)

3: Merge onto SKOKIE BLVD. 3.0 miles (4.9 km)

4: Turn LEFT onto DEMPSTER ST. 1.9 miles (3.0 km)

5: Turn RIGHT onto MCCORMICK BLVD. 0.8 miles (1.4 km)

TOTAL ESTIMATED TIME & TOTAL DISTANCE AFTER PASSING SIX FLAGS THEME PARK: 45 minutes 33.0 miles (53.0 km)

(directions provided by www.MapQuest.com)