AFIK, Georgetown was excluded because the local residents didn't want subway service. The same goes for JHU in Baltimore.

My DC v Shanghai comparison was a bit unfair, now that I think about it; while Beltway traffic might suggest otherwise, Shanghai's commuter population is an order of magnitude greater than DC's --> 3 minute intervals make sense.

Switching subtopics, I would have rated HK #1 if we started this thread 20 years ago. BUT, the HK Station to Island Line (Central) transfer is really bad (i.e. making people tote their luggage 500 meters should be out of bounds).