Interactive map of all chess clubs
Here is some statistics on Affiliates located in MA. You can get the list here:
http://www.uschess.org/index.php?option=com_wrapper&Itemid=198
Here is the table of the number of tournament per affiliate for the past year.
Certainly, one tournament gets 10 players, and other gets 100, so this is only an approximate value of activity by each affiliate.