Six Flags Great America is located equidistance between Chicago and Milwaukee. There are five easy ways to get here:
From Chicago: Take I-94 or I-294 West. Exit Grand Ave. (Rt. 132) East in Gurnee, Illinois. Six Flags is located immediately on the right. Approx. driving time: 45 minutes.
From Milwaukee: Take I-94 east. Exit Grand Ave. (Rt. 132) East in Gurnee, Illinois. Six Flags is located immediately on the right. Approx. driving time: 45 minutes.
From Western Illinois & Iowa: Take I-88 East to I-294 North in Illinois. Take I-294 North until it becomes I-94 West. Continue on 94 West and exit on Grand Ave. (Rt. 132) East in Gurnee, Illinois. Six Flags is located on the right. Approx. driving time: 3 hours.
From Indiana & Michigan: Take Tri-State Hwy. 80/94 West. Continue into Illinois and take I-294 West. Stay on 294 West until it becomes Interstate 94 West. Continue on I-94 West and exit on Grand Ave. (Rt. 132) East in Gurnee, Illinois. Six Flags is located on the right. Approx. driving time from the Illinois/Indiana border: 1 hour, 35 minutes.
OR Take the Skyway (I-90 West) through Chicago to the Dan Ryan Expwy. (I-90/94 West). Continue on I-90/94 West; it will become the Kennedy Expwy. 90/94 West near downtown Chicago. When 90/94 splits, continue on I-94 West. Exit on Grand Ave. (Rt. 132) east in Gurnee, Illinois. Six Flags is located on the right. Approx. driving time from the Illinois/Indiana border: 1 hour, 20 minutes.
From Peoria/Bloomington: Take I-55 North to I-294 West. Take I-294 West until it becomes I-94 West. Continue on I-94 West and exit on Grand Ave. (Rt. 132) east in Gurnee, Illinois. Six Flags is located on the right. Approx. driving time from Peoria/Bloomington: 3 hours.
Information taken from the Official Six Flags Great America Site