Clayton County was a battle site during the American Civil War, with the Battle of Jonesborough and the Battle of Lovejoy’s Station taking place in the area. Geography [ edit ] According to the U.S. Census Bureau , the county has a total area of 144 square miles (370 km 2 ), of which 142 square miles (370 km 2 ) is land and 2.8 square miles (7.3 km 2 ) (1.9%) is water. [5]