Five route numbers are duplicated in the system; the corresponding highways are in different regions, reducing potential confusion. In addition to primary highways in the contiguous United States, there are signed Interstates in Hawaii and unsigned Interstates in Alaska and Puerto Rico.
Five route numbers are duplicated in the system; the corresponding highways are in different regions reducing potential confusion In addition to primary highways in the contiguous United States there are signed Interstates in Hawaii and unsigned Interstates in Alaska and Puerto Rico