Montgomery County is a county in the U.S. state of Tennessee. As of the 2020 United States census, the population was 220,069. The county seat is Clarksville. The county was created in 1796. Montgomery County is included in the Clarksville, TN–KY Metropolitan Statistical Area.

Clarksville is the county seat of Montgomery County, Tennessee, United States. It is the fifth-most populous city in the state, after Nashville, Memphis, Knoxville, and Chattanooga. The city had a population of 166,722 as of the 2020 census.