Chicago area, just over the State Line into Northwest Indiana.
Regular Unleaded, which is 87 or 89 Octane is right around $4.00 per gallon, and that's here in Indiana. Illinois, especially the City (Chicago Proper) is at least $0.10 more. It varies from chain to chain, with chains like Speedway being the most expensive. I think the top price I've seen is about $4.30 per gallon. I think Mid Grade and Premium are 90 and 93 or 93 and 95 Octane are about $0.10 or so higher each grade.
Diesel is anywhere between $4.15-$4.25 per gallon. That's crazy to me, because for years diesel was cheaper than gasoline.
I'm lucky, because I have a newer car which even though it has a 6 Cylinder engine it gets about 25 MPG on average. I feel bad for people who've converted to Diesel or drive big SUV's. I have a 16 gallon tank and last time it cost me about $50 to fill up. (I usually would fill up from 1/4 tank) The people driving big vehicles with low MPG must really be paying through the nose.
There have been many instances of rigs at truck stops having their diesel siphoned out of them. There have also been instances of vandalism at parking lots. Cars have had their catalytic converters ripped from them. FYI, the catalytic converter helps with emissions, but hurts gas mileage.
About Ten years or so ago, I remember people being upeset about gas being $1.50-$2.00 per gallon. My how times change.