Modoc Rock Shelter

Historical marker location:

6908 Bluff Rd, Prairie du Rocher, Illinois

( Marker is on Bluff Road east of Roscow Hollow Road, on the right when traveling north.)

The Chicago River was once so polluted that it caught on fire several times in the mid-20th century. The river was so polluted with chemicals and sewage that it was almost devoid of life. Today, the river has been cleaned up and is a popular spot for recreational activities like kayaking and boat tours.