Sanilac Petroglyphs Historic State Park is a state park in the U.S. state of Michigan. The park, also known as ezhibiigadek asin consists of 240 acres (97 ha) in Greenleaf Township, Sanilac County, in Michigan's Thumb. It contains the largest collection of Native American petroglyphs in Michigan. The carvings were created in the pre-Columbian era and represent aspects of Native American spirituality. An interpretive hiking trail within the park passes along the nearby Cass River.