 In 1929, US 78's routing was split, with US 78N being designated on the northern branch of SR 8 (thereby replacing the mainline highway), while US 78S was designated on the southern branch of SR 8.Before 1932, US 78/SR 8 were paved from Carrollton to just southwest of Villa Rica, and from just west of Douglasville to Decatur.US 78/SR 10 were paved from Decatur to the DeKalb–Gwinnett county line; from about Bogart to about the Clarke–Oglethorpe county line; from east of the Oglethorpe–Wilkes county line to just south-southeast of Washington.