The Tennessee River rises from headwaters in the mountains of Tennessee, Virginia, North Carolina, and Georgia, with its main stream forming at Knoxville where the Holston and French Broad Rivers join. Its 41,000-square-mile valley receives an average of 52 inches of rain each year, and in water discharged into the Ohio and Mississippi Rivers, the Tennessee is about equal in size to the Missouri. The Tennessee Valley Authority harnessed the river through a multi-purpose system of dams and reservoirs that regulates floods, improves navigation, and generates electric power. High dams on tributaries create large storage reservoirs that hold back floodwaters and release them as needed to maintain downstream navigation depths while also producing electricity, helping protect the lower Ohio and Mississippi Valleys as well. Nine main-river dams with locks form a navigable 650-mile channel from Knoxville to the Ohio River, an important part of the nation’s inland waterway system connecting 20 states. After developing virtually all river power resources, TVA also built huge coal-burning steam electric plants to help meet the region’s growing power needs. Its power is sold at wholesale to cities and rural electric cooperatives for retail distribution to homes, farms, businesses, and industry, while a few large users, including U.S. Government defense installations, are served directly. The largest of these direct users are the atomic plants at Oak Ridge, Tennessee, and Paducah, Kentucky. Norris Dam, on the Clinch River, stores water that helps control floods; when released, that water generates electricity and helps maintain navigation depths on the Tennessee, and before reaching the Ohio River it produces electricity at nine additional dams.