Pere Marquette State Park Trail is a standout hiking destination in Grafton, IL, covering 15.0 miles with 1500ft of elevation change. Stats: 15.0 miles, 1500ft gain, Hard. Type: Loop. Surface: Rocky. Time: 7 hours. Fee: Free. Dogs: Yes, on leash. Permit: No. Wildlife: deer, eagles, turkeys. Best seasons: Largest state park in Illinois. Pack water, layers, and appropriate footwear. Conditions vary across IL. Leave No Trace: stay on trail, pack out all waste, respect wildlife.