Many settlers were drawn to the area by the lottery system, which gave them a chance to acquire homesteads from these newly available lands. The state's fifty-ninth county was named in honor of the noted Georgia lawyer Stephen Upson (1784/5-1824) four months after his death. It is the birthplace of John Brown Gordon, a major general in the Confederate army and a governor of Georgia in the 1880s, and Eugene C. Gordon, a Confederate major in the Alabama Cavalry, who later developed Decatur, Alabama.
In March 1825 the justices of the inferior court bought land lot 217 in the Tenth District to build the courthouse and the jail. Thomaston, the county seat, developed around this site. Incorporated June 11, 1825, the town was named for General Jett Thomas, a hero of the War of 1812 (1812–15).
The majority of the settlers to Upson County came from the eastern counties of Georgia, between the Oconee River and Augusta. Some were wealthy planters who already owned many slaves. Developing plantations on the rich soil of the eastern section of Upson County, around the town of The Rock and along the Flint River, they primarily grew cotton as a commodity crop. Other settlers came from North Carolina and South Carolina. The first cotton mill in Upson County, the Waymanville or Franklin Factory, was built on Tobler Creek in 1833. In 1835 a group of New Englanders arrived to manufacture textiles.
The Old Alabama Stagecoach Road, a well-traveled stagecoach and wagon-freight line between Augusta and Columbus, ran from the northeastern section of Upson County, crossing the Flint River at Double Bridges over Auchumpkee Covered Bridge in the southwest. Double Bridges was the site where two bridges spanned either side of Owen's Island in the middle of the Flint River.
Lamar County - north
Pike County - north
Monroe County - northeast
Crawford County - southeast
Taylor County - south
Talbot County - southwest
Meriwether County - northwest