mikeintopeka is there a sign on the bridge crossing the Mississippi River back into IL advising you it's illegal to bring in contraband tobacco products?
No.
I used to live in central IL, close to Indiana border (Terre Haute). Back then, taxes were a lot lower in IN than IL, and whenever people would go over there shopping, they would(try) to load up on cigs. At various times, IL state police would set up road checks, and bust people. Moot point now that IN taxes are now higher than IL, for cigs anyway. MO cigs are maybe 1/2 the price of IL, so that explains the signs down there. Bootleggers.
iirc, a person was/is allowed to bring in 2 cartons only.