Georgia State Route 139 is a 29.8-mile-long (48.0 km) state highway in the northeast part of state of Georgia. It travels within portions of Clayton, Fulton, and Cobb counties and connects the southern suburbs of Atlanta with the town of Mableton, west of the city.

Clayton County is located in the north central portion of the U.S. state of Georgia. As of 2021, the population was estimated to be 297,100 by the Census Bureau. The county seat is Jonesboro.