List of original highways in Louisiana (1–50)

Louisiana State Route 1 ran in a north–south direction from Pointe à la Hache to the Texas state line near Greenwood. The route was designated along the Jefferson Highway, an auto trail that ran from New Orleans to Winnipeg. In 1926, US 71, US 171, and US 80 were overlaid on SR 1 from Baton Rouge to Clarence, Belmont to Shreveport, and Shreveport to the Texas state line, respectively. While the routes were signed concurrently, the state route designations were removed in the 1955 Louisiana Highway renumbering. ==Louisiana State Route 2==

Louisiana State Route 2 ran in an east–west direction from the Texas state line via Lake Charles, Lafayette, Morgan City, and New Orleans to the Mississippi state line. The route was designated along the Old Spanish Trail. In 1926, US 90 was overlaid on most of SR 2. While the route was signed concurrently, the SR 2 designation was removed in the 1955 Louisiana Highway renumbering. ==Louisiana State Route 3==

Louisiana State Route 3 ran in a north–south direction from Baton Rouge to the Arkansas state line north of Lake Providence. The designation existed in two segments as the roadway passed through the state of Mississippi between a point north of St. Francisville and Vidalia (opposite the Mississippi River from Natchez, Mississippi). North of Vidalia, the route also passed through St. Joseph, Newellton, and Tallulah. In 1926, the southern segment became part of US 61, and the northern segment became part of US 65 when the numbered U.S. Highway system was created. Route 3 remained co-signed with its U.S. counterparts until the 1955 Louisiana Highway renumbering, which eliminated such overlaps. ==Louisiana State Route 3-D==

Louisiana State Route 3-D ran in a north–south direction from US 65/SR 3 north of Lake Providence to US 65/SR 3 at Millikin. It was a portion of SR 3 bypassed in 1931. ==Louisiana State Route 4==

Louisiana State Route 4 ran in a north–south direction from the Mississippi state line to LA 1 in Shreveport. The route was designated along the Dixie Overland Highway. In 1926, US 80 was overlaid on the entirety of SR 4. While the route was signed concurrently, the SR 4 designation was removed in the 1955 Louisiana Highway renumbering. ==Louisiana State Route 5==

Louisiana State Route 5 existed from 1921 to 1955. ==Louisiana State Route 5-D==

Louisiana State Route 5-D existed from 1921 to 1955. ==Louisiana State Route 6==

Louisiana State Route 6 ran in an east–west direction from the Texas state line at the Sabine River to the Mississippi state line at Vidalia. In 1934, US 84 was extended on top of the eastern half of SR 6 from the Mississippi state line to Clarence. While the route was signed concurrently, the state route designation was removed in the 1955 renumbering; the western half became the modern LA 6. ==Louisiana State Route 7==

Louisiana State Route 7 ran in a west–east direction from the Texas state line at the Sabine River to the Mississippi state line at Bogalusa. In 1926, US 190 was overlaid on SR 7 from Ripley to the Mississippi state line. While the route was marked concurrently, the SR 7 designation was cancelled in favor of US 190 in the 1955 renumbering. The remainder of SR 7 became LA 12. ==Louisiana State Route 8==

Louisiana State Route 8 ran in a north–south direction from US 71/SR 55 north of Shreveport to the Texas state line northwest of Rodessa. The route became the northernmost of LA 1 in the 1955 Louisiana Highway renumbering. ==Louisiana State Route 9==

Louisiana State Route 9 existed from 1921 to 1955. ==Louisiana State Route 10==

Louisiana State Route 10 ran in a north–south direction from the Arkansas state line near Plain Dealing to Bossier City. SR 10 became LA 3 in the 1955 renumbering. ==Louisiana State Route 10-D==

Louisiana State Route 10-D existed from 1921 to 1955. ==Louisiana State Route 11==

Louisiana State Route 11 existed from 1921 to 1955. ==Louisiana State Route 12==

Louisiana State Route 12 ran in a general north–south direction from Creston to Homer. The route became the central portion of LA 9 in the 1955 renumbering. ==Louisiana State Route 13==

Louisiana State Route 13 ran in an east–west direction from US 71/SR 10 at Loggy Bayou to US 80/SR 4 west of West Monroe. The route was split among seven different routes in the 1955 Louisiana Highway renumbering. ==Louisiana State Route 14==

Louisiana State Route 14 ran in a north–south direction from US 71/US 167/SR 1 in Alexandria to the Arkansas state line near Mer Rouge. In 1926, US 165 was overlaid on the entirety of SR 14. While the route was signed concurrently, the state route designation was removed in the 1955 renumbering. ==Louisiana State Route 14-D==

Louisiana State Route 14-D existed from 1921 to 1955. ==Louisiana State Route 15==

Louisiana State Route 15 ran in a north–south direction from US 65/US 84/SR 6 in Ferriday to SR 11 in Farmersville. SR 15 became the modern LA 15 in the 1955 renumbering. ==Louisiana State Route 15-D==

Louisiana State Route 15-D ran in a south–north direction from US 65/SR 16 near Red Gum to US 65/SR 3 in Clayton. ==Louisiana State Route 16==