In the original Louisiana Highway system in use between 1921 and 1955, the modern LA 6 comprised the western segment of the original State Route 6, a rare case of numerical duplication between the two systems. While Route 6 was a cross-state route, the current highway only covers one-third of its counterpart's former route. From the present eastern terminus in Clarence, Route 6 continued eastward through Winnfield, Jena, Jonesville, and Ferriday to the Mississippi state line at Vidalia, located opposite the Mississippi River from Natchez. In 1934, US 84 was extended west into Louisiana over this route. While the pre-1955 system maintained state route designations on all U.S. Highways in the state, the 1955 Louisiana Highway renumbering eliminated unnecessary concurrencies of this sort, leaving only US 84 on the eastern segment.