Lock and Dam No. 18 Historic District

Lock and Dam No. 18 spans the Upper Mississippi River near Gladstone, Illinois, where the river is more than a mile wide. The district covers about 205 acres and includes a lift lock with a 10.5-foot lift, an incomplete auxiliary lock, a central control station, a dam with 13 Tainter gates and three roller gates, long earth dikes and an 11-acre esplanade. Contractors built most of it between 1934 and 1937, and it opened to navigation on September 8, 1937, as the eleventh complex of the 9-foot channel project. It matters for its role in river transportation and for its engineering. The dam's submersible, elliptical Tainter gates use a revised girder frame and are unique, since no others were built. A guard wall added in 1941 and a guide wall extension in 1951 addressed outdraft problems. Later rehabilitation replaced much machinery, yet the lock, dam and setting remain largely as they were in 1948.