U.S. Highway 90 (US 90), one of the major east–west U.S. Highways in the Southern United States, runs through southern Louisiana for 297.6 miles (478.9 km), serving Lake Charles, Lafayette, New Iberia, Morgan City, and New Orleans. Much of it west of Lafayette and east of New Orleans has been supplanted by Interstate 10 (I-10) for all but local traffic, but the section between Lafayette and New Orleans runs a good deal south of I-10.

Lake Charles is the fifth-most populous city in the U.S. state of Louisiana, and the parish seat of Calcasieu Parish, located on Lake Charles, Prien Lake, and the Calcasieu River. Founded in 1861 in Calcasieu Parish, it is a major industrial, cultural, and educational center in the southwest region of the state. As of the 2020 U.S. census, Lake Charles's population was 84,872.