Interstate H-201

Interstate H-201 (H-201) is the only auxiliary Interstate located outside the Contiguous United States, on the island of O‘ahu in the U.S. state of Hawaii. The H-201 designation is also known as the Moanalua Freeway. The loop route connects exits 13 and 19 on H-1, passing Fort Shafter, Tripler Army Medical Center, and Red Hill. The highway is long.
Despite being designated an Interstate in 1989, until mid-2004 the route was an unsigned Interstate, signed only as Route 78.