Why “Mile 420” Keeps Disappearing
The number 420 has long been associated with cannabis culture, so a highway marker reading “Mile 420” can attract attention well beyond its ordinary job of marking distance. Some drivers treat it as a joke or photo opportunity; others take the sign itself as a souvenir. When a marker is repeatedly stolen or vandalized, transportation crews have to replace it—an expense and safety nuisance for a sign that was supposed to be forgettable.
The 419.9 Workaround
A practical fix is to label the location “Mile 419.9” instead. The marker still points to almost exactly the same stretch of road, but it no longer displays the famous whole number that made it a target. It is a small adjustment to the sign, not a change in the highway’s route or a meaningful shift in where the mile is measured.
The workaround also shows a peculiar limit of road signage: a marker has to be clear enough to guide travelers, yet its exact label can become a magnet for behavior that has nothing to do with navigation. By shaving off a tenth of a mile, crews can make the sign less tempting—and keep it standing where drivers need it.
