Perhaps the best of these societies is in New York: http://www.ny3d.org/stereo_art/
There is a society in St. Louis and many other major cities.
International 3d Society: http://www.international3dsociety.com/International_3D_Society/HOME.html
National 3d Society: http://www.stereoview.org/
World wide societies:
http://www.stereoscopy.com/clubs/
Illinois: http://sites.google.com/site/northillinoisstereocameraclub/
Missouri:
Steven Best, 6943 Amherst Avenue, St Louis, MO 63130, USA
Tel: +1 (314) 863-2718