Area code 678 is an overlay covering much of metro Atlanta, Georgia, alongside 404 and 770. Introduced in 1998, it supports the region’s rapid urban and suburban growth. Atlanta is a major hub for business, transportation, media, and civil rights history. Ten-digit dialing is mandatory. 678 is common for mobile and business lines and is part of the city’s identity as a sprawling, diverse, and economically vital Southern metropolis.