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.