Kentucky Route 80 runs alongside the Russell Fork from Millard to just shy of the Virginia state line. There it turns northeasterly along the west bank of Grassy Creek, which lies inside Virginia and forms the line between Buchanan and Dickenson Counties, in order to avoid the deep gorge through Breaks Interstate Park. Route 80 soon crosses into Virginia, and continues to parallel Grassy Creek until the split with Hunts Creek, where it (and the county line) turns southeast to follow that creek. About halfway to the community of Breaks, SR 80 crosses the creek and county line.
SR 80 descends from Big A Mountain into a relatively flat area, where it runs cross-country and next to small creeks via Honaker, the junction with State Route 67, and a bridge over the Clinch River at Blackford to U.S. Route 19 at Rosedale. There it turns southwest with US 19, alongside Elk Garden Creek, to Smithfield, where it splits to the south. SR 80 again runs cross-country past Rockdell, where it begins to climb Clinch Mountain, which it crosses (into Washington County) at Hayters Gap.
The road from Lodi to Cedarville, now State Route 803, was planned as part of State Route 12, the predecessor to U.S. Route 58, in 1923.[6] The next year, however, SR 12 was realigned to pass through Damascus,[7] and the road from State Route 10 (now U.S. Route 11) at Cedarville towards Lodi for five miles (8 km) was added to the state highway system[8] as State Route 125, a spur of SR 12. The next year it was extended southeast the rest of the way to SR 12 at Lodi and northwest 1.1 miles (1.8 km) to Meadowview.[9]
Five miles (8 km) of road northwest from Meadowview and three miles (5 km) southeast from State Route 11 (now U.S. Route 19) near Rosedale were added to the state highway system in 1928 as State Route 111,[10] and SR 125 was renumbered as part of SR 111 that same year. The gap was closed in 1930 and 1931.[11]