Louisiana Highway 3127 (LA 3127) is a state highway in Louisiana that serves Ascension, St. James, St. John the Baptist, and St. Charles Parishes. It spans 42.1 miles (67.8 km) in a northwest to southeast direction. It parallels LA 18 along the west bank of the Mississippi River, providing a much shorter inland bypass of the River Road. It is bannered in all four cardinal directions depending upon the part of the route.