[ardecila]

Peoria is disconnected from the Chicago economy, I don't see it rebounding without Cat. The only small Midwest cities that are doing well are those with a major corporate presence or a flagship university. Obviously Cat still employs a lot of people in the Peoria area, but it no longer has the top-level execs doing philanthropy in the community and organizing for outside investment - a good portion of the wealth generated is now being sucked out of that community.

Rockford has been in the doldrums for awhile; the only change on the horizon is rail service to Chicago.

As for Joliet, Aurora, and Elgin - they certainly stand to benefit from Chicagoland's growth, and IIRC they control the water supply in their respective territories so they have some leverage to annex the sprawling growth to their west. All 3 are within a semi-reasonable commute of Chicago, and all 3 have direct Metra service. They also have casino revenue to supplement their tax base, so they've been able to do downtown reinvestment to an extent. If they could somehow get a boost to their school systems, I think upper-middle class families would jump at the chance to buy a reasonably priced home in a walkable, tree-lined neighborhood.