Clarksville is a small township. It is located three kilometres southwest of Milton in the Otago region of the South Island of New Zealand. State Highways 1 and 8 meet in Clarksville. The town was also once the location of a railway junction, where the Roxburgh Branch left the Main South Line. Construction of this branch line began in the 1870s and Clarksville acted as the junction until 1907, when an extension of the branch was built alongside the Main South Line into Milton to improve operations. This led to Milton being the junction until 1960, when the extension was removed and Clarksville regained its status as a junction until the branch was entirely closed in 1968.