Which US cities have underground railways?
Background -- so, yesterday I was hacked off at one of the many ways that the iPhone is rubbish if you're outside mobile phone reception, and concluded that nobody with any influence at Apple had any experience of commuting by underground.
Edit: mr_tom has pointed out that some of the US urban railways are so close to the surface that mobile reception is maintained. So, I think I mean 'which US cities have underground railways that break mobile phone reception'.
And yes, I think I already knew that Cupertino was a driving sort of place.
- AKICIF: Subways