SR 129 begins in downtown South Boston at an intersection with southbound US 501, which comes from the northwest as two-way Wilborn Avenue and heads south as one-way Main Street. SR 129 heads northeast on Main Street, whose next intersection is with northbound US 501, which follows one-way Broad Street. The state highway curves northward and meets the west end of SR 34 (Hodges Street). SR 129 becomes Old Halifax Road shortly before making a westward curve to reach its northern terminus at US 501 (Halifax Road) in the hamlet of Centerville.[1][2]