770 Area Code – Marietta, Georgia: Location, Time Zone & History

The Home Depot's headquarters in Cobb County and the Lockheed Martin plant in Marietta, which has run the longest continuously operating military aircraft production line in history, both sit inside area code 770, the suburban ring that has wrapped around Atlanta since 1995. That year, 770 split off from area code 404, taking the territory outside Interstate 285 -- the Perimeter -- while 404 was reduced to an enclave covering inner Atlanta.

Growth in the metro area soon outpaced even that split. Area code 678 was overlaid on both 404 and 770 starting in January 1998, forcing mandatory ten-digit dialing across the region. Area code 470 followed as a further overlay in September 2001, and 943 joined the mix in March 2022 after approval from the Georgia Public Service Commission -- leaving five area codes (404, 678, 470, 770, and 943) sharing a single Atlanta local calling area today.

770 is often cast as 404's suburban and exurban counterpart, taking in Marietta, Alpharetta, Roswell, Sandy Springs, Duluth, and Peachtree City among others. Truist Park, home of the Atlanta Braves since 2017, sits in Cobb County's Cumberland area, inside 770 rather than the city of Atlanta itself. Alpharetta's technology corridor and Gwinnett County's logistics sector round out an economy long defined by aerospace, retail, and distribution.