The Illinois 911 Aerial Acquisition tiles can be viewed an downloaded at the ISGS clearinghouse.
There are also rest services available to pull in at: Folder: Imagery
They are the services with “2025” at the end. I believe the blocks go from North to South if you are looking for where your county/area would be included. I found my Northerly county in Blk1_West. (This aerial flight did not include Chicago or the collar counties).