Atlanta is a city in Logan County, Illinois, United States. The population was 1,692 at the 2010 census. The community was incorporated on …Atlanta is a city in Logan County, Illinois, United States. The population was 1,692 at the 2010 census. The community was incorporated on February 14, 1855. According to the 2010 census, Atlanta has a total area of 1.268 square miles, of which 1.26 square miles is land and 0.008 square miles is water.