U.S. Highway 171 (US 171) is a part of the United States Numbered Highway System and the only route within that system currently located entirely within the state of Louisiana. It spans 177.44 miles (285.56 km) in a north–south direction from the junction of US 90 and Louisiana Highway 14 (LA 14) in Lake Charles to the junction of US 79/US 80 and LA 3094 in Shreveport.