It is part of the Keokuk Lock & Dam, both of which are visible from a park at the foot of the commercial district. Built in 1913, the old lock was too small to serve the newer, larger barges. It was replaced in 1957 with a 1200' x 110' lock. At the time of construction in 1913, this was the longest dam in the world, with the longest transmission line and the highest voltage in the world. The Chief Engineer was Hugh L. Cooper.