Interstate H-201 is the only Auxiliary Interstate outside the Lower 48. It goes from Hawaii Route 99 in Aiea to Interstate H-1 in Honolulu. Until 2004 The Freeway was only signed as Hawaii Route 78. Signs mentioning Interstate H-201 Require a very thin font to fit all the characters. (Technically, Interstate H-201 is the nation's only 4 Digit Interstate.) The reason why they didn't sign the Interstate until 2004 is because of that thin font and Avoiding confusion between Interstate H-2 And itself.