The states are mandated to care for and improve the interstate highway system as needed, with some oversight from the federal highway administration. However, they are largely paid for with federal funds. Those funds have local match requirements where the states have to contribute a share to get the federal money. Usually 80% federal and 20% state, but that varies a little depending on the work being performed.Why does Hawaii have interstates?
If they called it a highway the state would actually have to pay for it. Call it an interstate and the federal government builds it(with our tax dollars). After that maintaining it is 80% federal and 20% state.Also...it connects our air base with our naval base.
I would wager the interstate in Hawaii is darn near paved with gold and well maintained.