Fort Randall Dam, South Dakota

The Fort Randall Dam is one of four dams on the Missouri River as it crosses South Dakota from north to south. It was constructed in the late 1940s and early 1950s by the Army Corps of Engineers, which maintains it to this day. The earthen dam is more than two miles wide, and forms Lake Francis Case behind it, which is the 11th largest reservoir in the nation. The dam produces up to 320 megawatts of electricity, and has a visitor center. These dams have tamed the river by turning it into a ribbon of swollen lakes for most of its course through the state.