Clarksville is a city in Johnson County, Arkansas, United States. The 2011 population estimate was 9,251. The city is the county seat of Johnson County. Clarksville is nestled between the Arkansas River and the foot hills of the Ozark Mountains and Interstate 40 and US Hwy 64 intersect within the city limits. Clarksville-Johnson County is widely known for its peaches, scenic byways and abundance of natural outdoor recreational activities.