Effigy Mounds National Monument in northeastern Iowa preserves one of North America’s most important protected collections of prehistoric earthworks, with 206 mounds across 2,526 acres, including 31 animal-shaped effigies. Built largely during the later Woodland period, these mounds stand at the western edge of the upper Midwest’s effigy-mound region along the Mississippi River near Harpers Ferry and Marquette. The site also lies in the rugged Driftless Area and remains culturally important to numerous present-day Tribal Nations. Established as a national monument in 1949 after work by Charles R. Keyes and Ellison Orr, it has also faced modern damage, theft, restoration, and efforts to rebuild trust with affiliated tribes.