We autocross mostly in Bellingham (near canada), but we hold events all over washington (boeing field in everett).
Big turnouts are fun to watch, but usaly dont get much seat time.
Our turnouts are around 20 cars. we run 2 groups, 2 times in the morning and 2 times in the afternoon, so a total of 12 runs each.
And then maybe a free run at the end if we finish early.
Our website:
http://www.chuckanutscc.org/