Atlanta had 34 participants. New York City had over 1200. I've never participated or watched, but I can't imagine how it's still funny with that many people.

Look at all those young people, all doing the same thing at the same time based on what somebody in the media said was cool awhile ago. What free spirited nonconformists they are. Plus you can see their butts.

This would be great in Pittsburgh if our subway had more than four stops and ran on weekends.

I did the Chicago one. It was totally disorganized, but still kinda fun. I rigged it so my warm-ups got caught in the door of the El and got ripped off of me, and subsequently had a hilarious conversation with a non-participant who kept apologizing for laughing at my "misfortune".