One of the most distinctive features of the Illinois Michigan Canal was a series of multiple locks between Chicago and LaSalle. The locks were needed because of the 140 feet height difference between Lake Michigan and the Illinois River. The total number of locks varied. Originally there were 17. In the 1870’s, two locks were eliminated.
The images included are of Lock 9 in Marseilles. This is the one feature that helps to identify this area as part or a canal.