The Tennessee River is the largest tributary of the Ohio River. It is approximately 650 mi (1,046 km) long, and located in the southeastern United States. It is formed at the confluence of the Holston and French Broad Rivers on the east side of Knoxville, Tennessee. From Knoxville, it flows southwest through East Tennessee toward Chattanooga before crossing into Alabama. It loops through north Alabama, eventually forming a small part of the state's border with Mississippi, before returning to Tennessee. At this point, it defines the boundary between Tennessee's other two traditional regions, Middle and West Tennessee. The final part of its run is in Kentucky, where it separates the Jackson Purchase from the rest of the state. It then flows into the Ohio River at Paducah, Kentucky. The river has been dammed numerous times, many of which were Tennessee Valley Authority and United States Army Corps of Engineers projects. The placement of the TVA's Kentucky Dam on the Tennessee and the Corps' Barkley Dam on the Cumberland River directly led to the creation of Land Between the Lakes. A navigation canal located at Grand Rivers, Kentucky links Kentucky Lake (the reservoir behind Kentucky Dam) and Lake Barkley (the reservoir behind Barkley Dam). The canal allows for a shorter trip for river traffic going from the Tennessee to most of the Ohio River, and for traffic going down the Cumberland River toward the Mississippi.