The Stone Mountain Freeway is a limited-access highway that connects Interstate 285 on the east side of Atlanta, Georgia, with the suburbs of Stone Mountain and Snellville before transitioning into an arterial road that continues to Athens. The freeway is signed as U.S. 78 for its entire length, with about half also being state route 410 in the west, and the eastern half being state route 10. It begins at the U.S. 29/78 split near Decatur, and continues east through eastern DeKalb and southern Gwinnett counties.

West of Interstate 285, the speed limit is 55 MPH (90 km/h). East of the junction with I-285, the limit rises to 65 MPH (105 km/h). Unlike Georgia's Interstate highways, the highway still has actual sequential exit numbers, rather than being mile-log.

Between I-285 in the west and Memorial Drive (Georgia 10) in the east, U.S. 78 overlaps 410; but, upon reaching 10, 410 ends and 10 merges with the U.S. highway.

The Stone Mountain Freeway shares state route number 10 with Freedom Parkway, a two-mile (3km) road in northeast Atlanta that connects with the Interstate highway system at a major highway interchange on the Downtown Connector. As that designation suggests, state officials originally intended the Stone Mountain Freeway to continue west, through Decatur, Druid Hills and Candler Park, to downtown Atlanta. In pursuit of those plans, in 1969 the GDOT purchased an X-shaped swath of land designed to carry two roads: Interstate 485, running from east to west, and another freeway connecting what are now Georgia 400 to the north and Interstate 675 to the south.[citation needed]

Neighborhood groups and local preservationists worked together to block road construction of the highways. After 20 years of litigation and political maneuvering, community groups and state and local officials in 1991 compromised and set much of the state-purchased right of way aside as parkland, later named Freedom Park. The land proposed as the interchange of the two cancelled highways, by then, had become the site of the Carter Center.

Freedom Parkway – the last vestige of the planned downtown link of the Stone Mountain Freeway – opened in 1994.