Arkansas Highway 400 (AR 400), also known as Shepherd Springs Road, is a short state highway in Crawford County.

At just over 2 miles (3.2 km), it serves as the entrance road for Lake Fort Smith State Park from U.S. Route 71 (US 71).

The route passes through the rugged terrain of the Ozark National Forest.

The highway descends down a steep hill, this section of road features a hairpin turn.

It continues to descend the hill until it reaches the entrance to Lake Fort Smith State Park, where the designation ends.