List of state highways in Hawaii

The Hawaii Department of Transportation maintains the smallest state-maintained system of state highways in the country. It consists of Interstates, state highways, and secondary state highways, totaling approximately 1,013 miles (1,630 km).

The state's four Interstates, all located on Oahu, are built to mainland standards unlike their counterparts in Alaska and Puerto Rico. The first three routes (H-1, H-2, and H-3) were approved in 1960, while an auxiliary route (H-201) was added in 1989.

Primary and auxiliary interstates

The Interstate Highway System was extended to Hawaii on August 29, 1960, a year after statehood, when the Bureau of Public Roads approved three routes—H-1, H-2, and H-3—for addition to the Interstate network. A fourth route, H-201, was later added in 1989 as an auxiliary designation for part of the Moanalua Freeway.

Unlike most Interstates on the mainland, whose primary purpose is civilian travel and interstate commerce, Hawaii's Interstates were built specifically to serve national defense needs by linking the island's scattered military installations. H-1 connects the Pearl Harbor naval complex and Hickam Air Force Base to a naval ammunition storage facility and the former Fort Ruger base at Diamond Head; H-2 connects to Schofield Barracks and Wheeler Army Airfield; and H-3 connects to Marine Corps Base Hawaii at Kāneʻohe Bay.

H-3 illustrates this defense purpose most directly. It satisfies the national defense purpose of connecting Marine Corps Base Hawaii with the US Navy port at Pearl Harbor via H-1, and opened on December 12, 1997 specifically to connect military personnel stationed across the island, linking the naval base at Pearl Harbor to the Marine Corps base on Oʻahu's northeast coast.