Denison Dam, 17,200 ft (5,243 m) long, on the Red River along the Texas–Okla. border, NW of Denison, Tex. The dam, built by the U.S. Corps of Engineers for flood control and hydroelectric power, was completed in 1944 and impounds Lake Texoma (227 sq mi/588 sq km), one of the largest artificial lakes in the United States. The lake is a major recreation area and has two national wildlife refuges along its shores.