Arlington, TX—1,200 people
http://conservativepabulum.vox.com/library/post/tea-party-arlington-texas.html
You can check to see if your tea party is listed HERE if not, post a comment on this thread citing the city, state and headcount.
Logan, Utah—100-150 people (estimate from pic)
http://hjnews.townnews.com/articles/2009/04/16/news/news01-04-16-19.txt
Thanks!