Louisiana’s highest speed limit is 75 mph (121 km/h), found on 154 miles of Interstate 49 in Saint Landry, Avoyelles, Evangeline, Rapides, Natchitoches, DeSoto and Caddo parishes. The 75 mph zone was established by the Louisiana Department of Transportation and Development. 70 mph (113 km/h) is posted on Interstates 10, 12, 20, 49, 55, 59, 220, and 310.
Most two-lane highways in Louisiana have a maximum speed limit of 55 mph (89 km/h).
A speed limit of 60 mph (97 km/h) is posted on I-10 in Lake Charles, Baton Rouge, and from LaPlace to New Orleans, I-12 in Baton Rouge, I-20 in Shreveport and Monroe, I-49 in Alexandria and Shreveport, I-310 in Destrehan, I-220 in Shreveport, U.S. Routes 71 and 167 in Kingsville, LA 3132, and Interstates 110, 210, 510, 610, and 910.
Speed and lane restrictions are in effect for trucks on the 18 mile (29 km) stretch of Interstate 10 known as the Atchafalaya Swamp Freeway. The restrictions lower the truck speed limit to 55 mph and restrict them to the right lane for the entire length of the elevated freeway.