The letter "R" prefix is followed by the number designation. Wisconsin is the only state to have a system of rustic roads. Wisconsin has a separate system of scenic byways following the development of a national system in the 1990s.
Following an "R" prefix, there is a numerical designation. Wisconsin stands alone with its rustic road system. Wisconsin maintains a separate network of scenic byways that emerged after the development of a nationwide system in the 1990s.