It spans 82.5 miles (132.8 km), following the east bank of Bayou Lafourche from Donaldsonville to Golden Meadow.

LA 308 is known as Bayou Road in Thibodaux and East Main Street south of Larose.

The route begins north of Golden Meadow at the Golden Meadow Bridge crossing over Bayou Lafourche from LA 1 and runs parallel with Bayou Lafourche and LA 1 heading north, passing through Galliano and Cut Off before entering Larose.

The highway then heads west along with Bayou Lafourche and LA 1, passing through St. Charles and enters Thibodaux.

The route then passes through Belle Rose and intersects LA 998 before continuing north towards Donaldsonville.