COMPEX (end of May) is, "annually, the largest 'local' stamp show in the U.S." - M&S-20070309:42 (x) (who cites "10 clubs")
9 clubs comprise COMPEX:
Austin Phil. Club,
Baden-Powell Phil. Assoc. of IL,
Chicagoland FDC Soc. (AFDCS Ch. 6),
Evanston-New Trier PS,
Germany PS of America - Ch. 5,
Israel-Palestine PS. of America,
North Shore PS,
UN Collectors of Chicagoland.
And I suppose the 10th would be COMPEX itself?