In United States Department of Agriculture: DOT in Illinois - TractorByNet.com

IL. but if memory serves farm tags for IL, allows truck to be driving 25 or 50 miles from primary property. and not allowed out of state. or something like that. for farmers it allows lower registration rate and for 2 years vs 1 year renewal. other words if you were X distance from your primary address of registration, you could get in trouble. and if ya go in or out of state you could also get i ...United States Department of Agriculture