Ours was last year and I think like 500-600 attended, but that is just a guestimate
Not that I know much about NPHC conventions, but I know from ours that most of the acitivities at convention are for "voting" delegates. There really isn't a plethora of activities for "non-voting" delegates to participate in. Last year, I was one of the, at most 100 non-voting delegates. On voting day, it's all day. I went to like 2 workshops and then spent the rest of the day (minus lunch & dinner) chillin in my room watching TV (the hotel was being remodeled, I don't think any of us found the pool
). I'm pretty sure that is why there aren't a lot of non-voting delegates.
I'm going to next years, I would like to be a voting delegate but either way I'm gonna go. It's in Orlando. I'm pretty sure I can find something to do on the day they are voting
