The Commuter is a science-fiction short story written by Philip K. Dick.
It tells the story of a railway station manager who encounters the eponymous commuter who testifies to the existence of a town that cannot be found on any normal map. There is clearly something amiss since the commuter exhibits a disconcerting tendency to literally vanish on close questioning about this ephemeral town. However, based on the information he manages to extract from the commuter, he undertakes an investigation and so boards the train the commuter swears is scheduled to stop at the town. Lo and behold, the station manager arrives at the non-existent town and further puzzling adventures ensue.
Subsequent investigation reveals the town nearly existed - it was narrowly voted out of existence during a planning meeting; the narrowness of the vote directly reflected in the ephemeral nature of the town.
As with so much of Dick's fiction, it is an exploration of a boundary of existence (cf "Do Androids Dream of Electric Sheep"—the boundary explored here was between the human and artificial). It is also very similar to a "Schrödinger's Cat" thought experiment—a manifestation of quantum effects in the macro world.