The Duck River of Tennessee is the longest river located entirely within the state of Tennessee.

The Duck River drains a significant portion of Middle Tennessee. It rises in hills near an area of Middle Tennessee known as the "Barrens", an area which was already found to have been deforested by white settlers upon their arrival. (Several theories have been advanced to explain this phenomenon.) It enters the town of Manchester, county seat of Coffee County, and meets its confluence with a major tributary, the Little Duck River, in an interesting and scenic setting in Old Stone Fort State Park.

Other major towns along the Duck include Shelbyville, Columbia, and Centerville. Above Shelbyville, the Duck is impounded by Normandy Dam, a Tennessee Valley Authority project of the early 1970s which was built for flood control and recreation. Normandy was not equipped for power generation as were previous TVA dams built in Middle Tennessee. The structure was named for the tiny hamlet of Normandy, which is nearby. The resultant reservoir occupies over 5,000 acres (20 km²) of what was previously prime land for agriculture. Further downstream, Shelbyville is protected from potential Duck River flooding by levees and floodgates. A dam, constructed by the Tennessee Electric Power Company across the river adjacent to downtown Shelbyville is a relic of the early electrical development of the area prior to the establishment of the Tennessee Valley Authority.

Downstream in Maury County is a Yanahli Wildlife Preserve, comprised of land which was meant to be another TVA reservoir. The Columbia Dam was never completed, however, when an endangered species of mussel was found in this section of the Duck and studies showed the project costs would far exceeed benefits. After years of litigation, the dam, which was largely completed, was dismantled at a loss approaching $80,000,000 of public funds. Another old TEPCO dam, somewhat similar to the one in downtown Shelbyville, is located downstream of the uncompleted dam site. Private funds have been spent on this dam to rehabilitate it to resume electrical power production; however, as of 2005, this has not proven to be successful. The Duck River frequently floods parts of Columbia, particularly the poorer neighborhoods near downtown. Columbia, with a population approaching 40,000, is by far the largest town along the Duck.

Between Columbia and Centerville, the Duck cuts through the Western Highland Rim and is joined by several major tributaries, notably the Piney River. Downtown Centerville is located high above the Duck River bottoms. The corn fields once visible from downtown there have been replaced by soccer fields in the Duck River bottoms as Centerville becomes something of a "exurb" of Nashville. Below Centerville, the Duck again enters a fairly rural, somewhat remote area. Its largest single tributary, the Buffalo River, reaches its confluence with the Duck in southern Humphreys County, just a few miles from the mouth of the Duck into the Tennessee River. The area of the mouth of the Duck is part of the Tennessee National Wildlife Refuge . The total length of the Duck River is over 240 miles (370 km).