Terminology
Terminology while the name implies that highways cross state lines, many Interstates do not. Somewhat, it is the system of interstates that connects states. There are interstate highways in Hawaii, funded in the same way as in the other states, but completely within the populous island of Oahu. They have the designation of H-X, and attach military bases. Similarly, both Alaska and Puerto Rico have public roads that get funding from the Interstate program, though these routes are not signed as Interstate Highways.