Smithland Locks and Dam is located on the Ohio River at mile 918.5 below Pittsburgh, Pennsylvania and 62.5 miles upstream of the confluence of the Ohio and Mississippi rivers. The locks are on the Illinois side of the Ohio River accessible via the New Liberty Road reached from either Golconda or Brookport, Illinois.
The Smithland Locks and Dam was authorized on December 8, 1965, as a replacement for existing Locks and Dam 50 and 51, under authority of Section 6 of the Rivers and Harbors Act of March 3, 1909.
Smithland Locks’ construction started in 1971 and was placed in operation 1979. The dam construction started in 1974 and was completed in November 1980. The two Smithland Locks are each 110 feet wide and 1,200 feet long. This was the first structure of this size on the Ohio River and was then the world’s largest twin navigational locks system. The overall length of the river lock wall, including the guard walls, is approximately threequarters of a mile. Each miter gate leaf weighs 250 tons. The miter gates and valve machinery are hydraulically operated. Each lock chamber requires eight minutes for filling and nine minutes for emptying.