St. Anthony Falls

Saint Anthony Falls, or the Falls of Saint Anthony, located at the northeastern edge of downtown Minneapolis, Minnesota, is the only natural major waterfall on the Mississippi River. Throughout the mid-to-late 1800s, various dams were built atop the east and west faces of the falls to support the milling industry that spurred the growth of the city of Minneapolis. In 1880, the central face of the falls was reinforced with a sloping timber apron to stop the upstream erosion of the falls.

Source: Wikipedia