No, I'm not trying to claim any credit, just adding another data point.

As a shop rat, I built my first fixed gear up in 1991 with a hub that some messenger bag guy brought back from Japan for me. Another wrench gave me a pair of track bars that he'd had hanging around since his junior days, and I had the stylingest nishiki in my high school.

I know E.Zo and some of the king boys were already riding fixed by that point, but yeah, like I said, most of the messengers I saw downtown were riding mountain bikes with the full metal baskets up front, although some had realized that they could chop the sides and front to make a sort of basket/rack thing.

I've never ridden in NYC. For all I know, it could've been a hotbed of fixed activity since the dawn of time. I'm just sharing what I've seen.