Needles Highway (SD-87)

Peter Norbeck mapped the entire route on foot and on horseback. The Needles Highway — the northern 14 miles of SD-87 — finished in 1922 and named for the high granite spires it winds among, passes through two tunnels blasted through sheer granite walls: Iron Creek Tunnel and Needles Eye Tunnel. The highway closes in winter. That, and the fact that it's almost exclusively used by sightseers, tells you most of what you need to know before you go.