"A Subway Named Mobius" is a 1950 science fiction short story by American astronomer Armin Joseph Deutsch.
Originally published in Astounding Science Fiction, it imagines the results of increasing the complexity of the Boston MTA system (now the MBTA) with a new interconnection.
It has been collected in anthologies since its original publication, and was nominated for a Retro Hugo Award in 2001, placing fourth in the final vote.
One day, after cautiously resuming using the MTA himself, Tupelo realizes he is on the missing train and that no time has passed for the passengers.
The story was the basis of the 1996 Argentine film Moebius, with the setting changed to Buenos Aires.