Clarksville is the county seat of Montgomery County, Tennessee, United States. It is Nashville, Memphis, Knoxville, and Chattanooga's fifth-largest city in the State. Estimated 2018 population of 156,794. It is the Clarksville's largest capital city, TN KY metropolitan statistical area, consisting of Tennessee counties of Montgomery and Stewart, and Kentucky counties of Christian and Trigg. Created in 1785 and incorporated in 1807, the city was named after General George Rogers Clark, frontier warrior and hero of the Revolutionary War.