Here's Illinois' lift law:
[FONT=Arial, Helvetica, adobe-helvetica, Arial Narrow]Illinois[/FONT]
[FONT=Arial, Helvetica, adobe-helvetica, Arial Narrow]You can't lift the body from the chassis more than 3 inches. In terms of bumper height, a 4,500-pound GVWR or less and your front bumper can't go higher than 24 inches, and the rear must be no more than 26 inches. GVWRs between 4,501 and 7,500 mean 27 inches at the front and 29 at the rear. Finally, if your truck is between 7,501 and 9,000, the allowable altering is 28 and 30 inches.[/FONT]
I'm originally from Illinois about 4 hours south of Chicago and I learned that it depends on what town you are in as to how much the law is enforced. In my hometown when I was in high school our cops didn't bother you as long as it was an actual lift kit and not some home grown kit that looked or was unsafe.
Rick