An unsigned highway is a highway that has been assigned a route number, but does not bear road markings that would conventionally be used to identify the route with that number. Highways are left unsigned for a variety of reasons, and examples are found throughout the world. Depending on the policy of the agency that maintains the highway, and the reason for not signing the route, the route may instead be signed a different designation from its actual number, with small inventory markers for internal use, or with nothing at all.

Skyline Drive is a 105-mile (169 km) National Parkway that runs the entire length of the National Park Service's Shenandoah National Park in the Blue Ridge Mountains of Virginia, generally along the ridge of the mountains. The drive's northern terminus is at an intersection with U.S. Route 340 (US 340) near Front Royal, and the southern terminus is at an interchange with US 250 near Interstate 64 (I-64) in Rockfish Gap, where the road continues south as the Blue Ridge Parkway. The road has intermediate interchanges with US 211 in Thornton Gap and US 33 in Swift Run Gap. Skyline Drive is part of Virginia State Route 48, which also includes the Virginia portion of the Blue Ridge Parkway, but this designation is not signed.