I remember those fines posted as you entered PA. It clearly stated that the fines start at 56mph. Now how could someone “maintain” 56 mph?
I saw a lot of out of state Cadillac, Mercedes, etc. that found out .... the radar read out said 56.
Although they don’t post their fines on signs, Illinois will run their speed traps on the interstates with out of state drivers being prime income. They generally setup a mobile payment center in a van near the speed trap. They then encourage you to pay on the spot (and they do take credit/debit cards) or you can go to the nearest town/county seat and spend a couple of days trying to get released on bond. Above all, never consent to allowing your car to be searched if you have a gun. Even if it is properly secured they will steal it, or if you protest will fake the circumstances and drag you off to the locals and steal it anyway. Or even better yet, just avoid the place.