The Hawaii Department of Transportation (HDOT) maintains the smallest state-maintained system of state highways in the country.

[1] The state's four Interstates, all located on O‘ahu, are built to mainland standards unlike their counterparts in Alaska and Puerto Rico.

Possibly ment to continue to Hawaii state highway 200 (saddle road) though unclear.

During World War II, a temporary Federal route numbering system was setup on the island of Oahu.

They were used to assist military personnel not accustomed to the Hawaiian street names during the time of Martial law in the Territory of Hawaiʻi from 1941 to 1945.