Mableton is an unincorporated census-designated place in Cobb County, Georgia, United States. As of the 2000 census, the CDP had a total population of 29,733. It was named for Robert Mable, who in 1843 bought 300 acres (about 120 hectares or 1.2 km²) of land on September 11. The Southern Railway opened a train station in Mableton in December 1881, and in 1882 the post office opened on June 28, replacing the Bryantville post office about two miles (3 km) southeast. In 1912 it was incorporated as a town on August 19, but in 1916 disincorporated on August 17. The historic original Mable House and plantation, located on Floyd Road just north of Clay Road, now includes an amphitheatre which hosts public events. Roy Barnes, governor of Georgia from 1999 to 2003, is from Mableton.