Movealongmovealong
Sharpshooter
I guess I stand corrected, sorry for the misinformation. I remember before traveling through Illinois a while back some research lead to information that peora had a ban on firearms.
I frequently travel to Peoria, and can vouch that while it is not illegal to own a handgun in Peoria (provided you have a FOID card), traveling with a gun in IL in general can be subject to local laws, many of which do place restrictions on firearms. If you stay on an interstate highway, generally, you should be ok to transport (as others have said, if done so properly), however I would be very hesitant to travel all around (esp in cities, whose laws I am not familiar with) in IL with a firearm.
Some counties' sheriffs have announced recently that they would not even allow their deputies to arrest people for certain firearms transport technical violations, but YMMV, and I'm not risking a felony for a "maybe." Most of those counties are downstate.