. . . was proclaimed on October 25th, 1949. It is one of two National Park Service sites in Iowa (the other being Herbert Hoover National Historic Site).
The mounds preserved here are considered sacred by many Americans, especially the Monument’s 20 culturally associated American Indian tribes. A visit offers opportunities to contemplate the meanings of the mounds and the people who built them. The 200 plus American Indian mounds are located in one of the most picturesque sections of the Upper Mississippi River Valley.
The Late Woodland Period (1400-750 B.P.) along the Upper Mississippi River and extending east to Lake Michigan is associated with the culture known today as the Effigy Moundbuilders. The construction of effigy mounds was a regional cultural phenomenon. Mounds of earth in the shapes of birds, bear, deer, bison, lynx, turtle, panther or water spirit are the most common images. Like earlier groups, the Effigy Moundbuilders continued to build conical mounds for burial purposes, but their burial sites lacked the trade goods of the preceding Middle Woodland Culture. The Effigy Moundbuilders also built linear or long rectangular mounds that were used for ceremonial purposes that remain a mystery. Some archeologists believe they were built to mark celestial events or seasonal observances. Others speculate they were constructed as territorial markers or as boundaries between groups.
The animal-shaped mounds remain the symbol of the Effigy Mounds Culture. Along the Mississippi River in northeast Iowa and across the river in southwest Wisconsin, two major animal mound shapes seem to prevail: the bear and the bird. Near Lakes Michigan and Winnebago, water spirit earthworks—historically called turtle and panther mounds—are more common.