Louisiana Highway 1 (LA 1) is a state highway in Louisiana. At 431.88 miles (695.04 km), it is the longest numbered highway of any class in Louisiana. It runs diagonally across the state, connecting the oil and gas fields near the island of Grand Isle with the northwest corner of the state, north of Shreveport.

Grand Isle is a town in Jefferson Parish in the U.S. state of Louisiana, located on a barrier island of the same name in the Gulf of Mexico. The island is at the mouth of Barataria Bay where it meets the gulf. The town of Grand Isle is statistically part of the New Orleans−Metairie−Kenner metropolitan statistical area, though it is not connected to New Orleans' continuous urbanized area.