TENNESSEE RIVER, the largest tributary of the Ohio river, U.S.A. It is formed by the confluence of the Holston and the French Broad rivers 4.5 m. above Knoxville, Tennessee, flows S.S.W. to Chattanooga, there turns W. through the Cumberland Plateau and into the N.E. corner of Alabama, continues W. across the northern part of Alabama, turns N. on the boundary between Alabama and Mississippi, and continuing N. across Tennessee and Kentucky unites with the Ohio at Paducah. Its principal tributaries rise in the Appalachian Mountains: the Holston and the Clinch on the mountain slopes that flank the Appalachian Valley in western Virginia; and the French Broad, the Little Tennessee, and the Hiwassee in the mountains of western North Carolina. The Tennessee itself is 652 m. long, and with the Holston and the North Fork of the Holston forms a channel about 900 m. long. Its drainage basin covers about 44,000 sq. m., and its low water discharge at Paducah is 10,000 cu. ft. per second. Its average fall is 0.79 ft. per mile: 0.956 ft. from Knoxville to Chattanooga; 1.19 ft. from Chattanooga to Florence, Alabama; and 0.39 ft. from Florence to its mouth. The banks are everywhere easily accessible except at Knoxville and Chattanooga, where, for short distances, high elevations rise precipitously from the water; and as the banks are mostly of clay or rock the channel is permanent and the river is unusually free from silt.
The Tennessee is navigable by steamboats throughout its entire course of 652 m. for several months of the year; its tributaries have a nearly equal navigable mileage, and the main river and its tributaries together have a navigable mileage for rafts and flatboats of 2400 m. At low water there are three obstructions to steamboat navigation in the main stream: the Colbert and Bee Tree shoals, just below Florence; the Muscle shoals just above Florence; and Hales Bar, 33 m. below Chattanooga. The state of Alabama, aided by the Federal government, constructed a lock canal, affording a depth of 5 ft., around the Muscle shoals in 1831–1836, but because of the obstructions above and below the canal was little used and was soon abandoned. The Federal government, beginning in 1868, completed the reconstruction of the Muscle Shoals Canal in two divisions (one 3.5 m. long with two locks, the other 14.5 m. long with nine locks, and both providing a depth of 5 ft.) in 1890, began in 1893 the construction of a canal, about 8 m. long and with one lock, around Colbert and Bee Tree shoals, and in 1904 authorized the construction with private capital of a lock and dam at Hales Bar to provide a channel 6 ft. deep at low water between it and Chattanooga, the water power to be used by the persons furnishing the capital. In 1905 a committee of the United States Senate recommended that future improvements of the river be made with a view of obtaining ultimately a channel having a minimum depth of 12 ft. at low water; and in 1907 Congress adopted a project for deepening to 5 ft. at low water the channel (145 m. long) between Hales Bar and the Muscle Shoals Canal. In 1908 the commerce carried on the Tennessee between Chattanooga and Paducah amounted to 755,010 tons, valued at $18,752,180; it consisted chiefly of general merchandise, farm products, forest products and iron ore in the upper section, of general merchandise, cotton, timber products and) grain in the middle section, and of general merchandise, farm products and timber products in the lower section.
During the Civil War Fort Henry was erected by the Confederates on the Tennessee river, in Tennessee just below the Kentucky state line, and on the 6th of February 1862 was captured by Com. A. H. Foote; Fort Donelson on the Cumberland, several miles east, was captured on the 16th by General U. S. Grant, and the two rivers were thus opened for the advance of the Federals far into Confederate territory.