National Park Service Passport Stamp
The National Park Service (NPS) Passport is a means of recording visits to the different NPS sites with a rubber cancellation stamp.
While the Chicago Portage was designated a National Historic Site by the NPS, it is one of the 49 National Historic Sites which are not owned by the NPS. So there is no visitor center, no NPS staff in "Smoky the Bear" hats, and no NPS Passport Stamp cancellation at the actual historic site.
But the NPS Passport Stamp for the Chicago Portage IS available at The Little Red School House Nature Center (in the Cook County Forest Preserve) at 9800 S. 104th Ave. in Willow Springs (708-839-6897).