Hartsville is a town in Trousdale County, Tennessee, United States. It is the county seat of Trousdale County, with which it shares a consolidated city-county government. The population of Hartsville was 2,395 at the 2000 census, but after consolidation with the county in 2001, the population of the consolidated entity became equal to that of the county (7,259 in 2000). Hartsville is the county seat of Trousdale County, Tennessee and now coextensive with it as a metropolitan government by virtue of a referendum which passed in Trousdale County by a single vote. Trousdale County High School is located here, as well as a technical school operated by the Tennessee Board of Regents. Trousdale County is one of two counties in Tennessee to have legalized parimutuel betting on horse racing, but no group has ever stepped forward to build a racetrack. Hartsville is located slightly north of the Cumberland River and is approximately fifty miles northeast of Nashville. In 1977, the Tennessee Valley Authority began construction on the Hartsville Nuclear Plant, but cancelled the project in 1984 after spending nearly two billion dollars. The plant's unused cooling tower dominates the view south from State Route 25 between Smith County and Trousdale County.