Jefferson County is a county located in the U.S. state of Georgia. As of the 2020 census, the population was 15,709. The county seat and largest city is Louisville. The county was created on February 20, 1796, and named for Thomas Jefferson, the main author of the Declaration of Independence who became the third president of the United States.

Louisville is a city in and the county seat of Jefferson County, Georgia, United States, and also a former state capital of Georgia. It is located southwest of Augusta on the Ogeechee River, and its population was 2,493 at the 2010 census, down from 2,712 at the 2000 census. By 2020, its population was 2,381. Its name is pronounced "Lewis-ville", though it and the differently pronounced city in Kentucky were both named for Louis XVI.