I'm looking at the map of Northeast Illinois and the Chicagoland area in Feral Cities.

Actually, as a friend is from there, I've gone over the Chicago section of Feral Cities a few times - it caught my eye.

Lake County, IL. IRL, not-very-densely populated - holds the base where the Navy does its basic training (Great Lakes Naval Base).

Very much suburbia. Thinking of towns like Gurnee, Libertyville, etc. seems to scream "suburban prototype" to me.

I'm trying to figure out:

Pre-CZ, was it part of Chicago? Suburbs? What?
Post-CZ...Is it in the Corridor? Did the writers mean for areas like that to be sub-sprawl? Part of South Milwaukee?

More than likely, Lake County was part of the Chicagoland sprawl before things went to hell. The megaplexes tend to cover a lot of territory - and locations that are almost part of a given city in the present day were more than likely fully-incorporated by the 2050's. Many suburbs became middle to upper-class neighborhoods. Or, if they were in largely industrial areas, D- and Z-zones. Since this was a military area, it's most likely the former. Post-CZ, I suppose it would depend entirely on it's distance from the CZ proper. Though, again, as a military area, it was probably a refuge for the "right" people fleeing from the Zone.

'Course, I don't think they ever specified anything (unless it's in Bug City somewhere). So this is all guess-work on my part.