Decatur is a city in, and the county seat of, DeKalb County, Georgia, United States and is part of the Atlanta metropolitan area. With a population of 20,148 in the 2013 census, the municipality is sometimes assumed to be larger since multiple zip codes in unincorporated DeKalb County bear the Decatur name. The city is served by three MARTA rail stations. The city is located approximately 5 miles northeast of downtown Atlanta and shares its western border with Atlanta.