Atlanta was an American city, located in the state of Georgia. (TV: Dead of Night)
The Centers of Disease Control (CDC) was based here. (PROSE: Spore)
Behind the scenes
Location information
Though it's possible that a real world location doesn't exist in the same geographic space in the Doctor Who universe, such cases are few and far between. Thus, the map to the right is probably a good indicator of the DWU location of Atlanta.