when louisiana numbered its state highways in 1921, the entire length of the jefferson highway through louisiana was designated as state route 1. this route was in effect until the 1955 louisiana highway renumbering. when the u.s. highway system was designated in 1926, the jefferson highway was split into four u.s. highways in louisiana: us 61 from new orleans to baton rouge (before it was re-routed onto the airline highway), us 71 from baton rouge to clarence, us 171 from mansfield to shreveport, and us 80 from shreveport west into texas. the section between natchitoches and mansfield was not included in the u.s. highway system.