Lock and Dam No. 8 at Genoa, 679.2 miles above the mouth of the Ohio River, was built on a foundation of sand, gravel, and broken rock. It has a 110-foot-wide chamber and an 11-foot lift from the lower to the upper pool. Construction cost $6,702,500 and affected 18,591 acres of land. In May 1937, the battery of fifteen gates closed and the Genoa Dam opened for navigation. It was one of 26 locks and dams built by the United States Government to improve transportation from Minneapolis to the mouth of the Missouri River. The project, approved by Congressional Act on August 30, 1935, was largely completed by 1938. In the next fifteen years, river traffic increased from 458 to 2,636 million tons.