Bay City State Park - Fall Campground Harvest Festival and Trunk-or-Treating 3582 State Park Drive Bay City, MI 48706 989-684-3020 Dates: September 28, 2019 - October 12, 2019 Recurrence: Recurring weekly on Saturday Location: Bay City State Park Phone: 989-684-3020 Time: For times contact the Park. Price: Free / Park entry requires a DNR Recreation Passport. Email Website Details Join our Fall Festival Weekends with daytime activities geared for our campground guests with fun crafts and treats, pumpkin seed spitting and campsite decorating contests and trick-or-treating. *The public is welcome to trick-or-treat. Any non-registered campers can set up a candy station by their vehicle (Truck-or-Treat style) and bring enough candy for at least 1,200 kids.