Louisiana Highway 21 (LA 21) is a state highway in Louisiana that serves St. Tammany and Washington Parishes. It spans 51.76 miles and is bannered north/south.
Route description
From the south, LA 21 begins at an intersection with Louisiana Highway 22 in Madisonville and heads northeast, intersecting with Interstate 12 and U.S. Route 190 in Covington. It continues northeastward, entering a brief concurrency with Louisiana Highway 40 in Bush for less than one mile. Between Bush and Sun, LA 21 widens to a four lane, divided highway after merging with Louisiana Highway 41, continuing due north from the merge. LA 21 then intersects LA 10 in Bogalusa, then runs north through Varnado and Angie before becoming Mississippi Highway 35 at the state line