Billboards are ubiquitous features of American highway road trips. Unless, that is, you're driving through Hawaii, Maine, Vermont, or Alaska. All four states have banned billboards, starting with Hawaii in 1927. The ban was made to preserve the islands' natural beauty, and Vermont jumped on the bandwagon for similar reasons in 1968. Maine followed suit in the early '80s, and Alaska put up its own billboard ban in 1998. Of these four states, Hawaii retains a unique distinction: it was the only state to ban billboards before it even officially became a state.