Sanilac Petroglyphs Historic State Park preserves Michigan’s largest collection of Native American petroglyphs, carved into a sandstone outcrop in the Thumb and linked by trail to the Cass River floodplain forest. Created in the pre-Columbian era, likely between 300 and 1,400 years ago, the roughly 165 carvings reflect Great Lakes Native American spirituality and teachings through images such as handprints, swirls, lines, and figures including Ebmodaakowet, Migizi Inini, and Mishibizhew. Archaeological finds show the area was used periodically for 8,000 years. Since the late 19th century, preservation and study have expanded, culminating in state protection, digital documentation, and since 2019, co-management by Michigan and the Saginaw Chippewa Nation.