The route continues through Johnson, Martin and Lawrence counties to terminate at another junction with U.S. Highway 23 south of Catlettsburg in Boyd County.

From South Catlettsburg to Louisa it follows the original routing of U.S. 23.

The road continues 8 miles (13 km) to the Lawrence County line.

In Lawrence County, it passes KY-1 and KY-1185, which takes you to Yatesville Lake.

Kentucky Route 3 Spur (KY 3 Spur) is a short 0.053-mile (85 m) spur of KY 3 in Louisa running northeast to the West Virginia border at the Tug Fork of the Big Sandy River, where it continues into that state as West Virginia Route 37.