jmp316 wrote:Great idea. As an FYI, the Illinois link sent in the original post is very old and should not be used to gather current information on streets.
Yes, it does look like that IDOT general maps site contains older versions of the highway maps. At least the one township and one county I checked were last updated in the 90s.
The parent page
has links maps such as the 5-year functional classification maps which have been updated more recently. Each county (we have 182) might have maps available on its own website.
There is a group of Illinois editors working on getting the state wiki pages, including reference info, in order so I'd recommend that (link is in my sig) for updated IL-specific resources going forward.