Why Does Hawaii Have Interstate Highways?
While we'd like to believe Hawaii's Interstate system was created for the sole purpose of annoying the late George Carlin, the name is actually a misnomer. Not all Interstates physically go from one state to another; the name merely implies that the roads receive federal funding. The three Hawaii Interstates (H1, H2, and H3) became Interstates as part of The Dwight D. Eisenhower System of Interstate and National Defense Highways to protect the U.S. from a Soviet invasion by making it easier to get supplies from one military base to another.
This explanation originally appeared in the "25 Most Important Questions in the History of the Universe" issue of mental_floss magazine.