A sampling from Google of the estimated sizes of the crowds Ron is drawing across the states:
Chico State University- 3,000 (according to CNN it was 6,200)
Bonner County Fairgrounds- 1,200
Louisiana College- 1,100
University of Maryland- "nearly 2,000"
Springfield, Virginia- 2,000, with about another 500 turned away.
UCLA (record breaker)- estimates range from 7,000+ to 10,000, with hundreds more turned away. Around 8,000 seems most likely; estimates vary based on conflicting reports of capacity for the tennis court.
Texas A&M- 3,000
University of Wisconsin- 5,200
Berkeley- "more than 1,000" according to the Daily Cal.
Denver- "more than 1,150"
Austin- 6,000 at a town hall meeting according to Jack Hunter (Daily Paul), 4,000 according to local sources.
Houston, 4/27/12- 3,000 (according to Jack Hunter)
UCSD, 5/4/12- est. 3,500