A Subway Named Mobius (1952)

I guess OP was reading the same r/boston thread!

What I enjoy about this story is that it imagines a world where the MBTA (Boston's public transit system) was so well funded to become an incredibly complex system. In reality there hasn't been significant improvement since the late 80's, and Green Line service to Forest Hills is still "temporarily" suspended.

There's a movie called Moebius based on this

https://en.wikipedia.org/wiki/Moebius_(1996_film)

I ruptured out of suspension of disbelief the moment I read "The missing persons did not return. In the large, they were no longer missed"... Really? No longer missed? 400 people disappear out of thin air and that's it. No "Thoughts and Prayers"? No middle eastern 3rd world country to wipe out of existence? Seems to me like a veeeery unrealistic waste of political leverage to gain...

I first read this delightful story (and the Heinlien story) about 1968 (my 7th grade year) in a Clifton Fadiman anthology entitled “Fantasia Mathematica.” He also edited another anthology, “The Mathematical Magpie.” I’ve always been terrible at math, but loved stories about mathematics. This book, at least, was heavy on the topology stories.

Also fun, along the same lines: "And He Built a Crooked House", by Robert Heinlein (https://en.wikipedia.org/wiki/%22%E2%80%94And_He_Built_a_Cro...)

I've always loved this story, I (incorrectly) remembered the topologist calculating that there must always be one train missing