Weinstein teamed with client Lew Russfield, owner of Sun Valley Skiwear, to help organize the National Ski Equipment and Clothing Association in 1954, with Russfield as president and Weinstein as counsel. In 1959 the group changed its name to Ski Industries America (SIA). Weinstein also organized and ran the National Ski Credit Association, a credit reporting agency.
Weinstein's influence on SIA activities and administrators was considerable. "He [Weinstein] had a huge impact on the business professional I am today and somehow managed to keep me on the straight and narrow,"said SIA president David Ingemie. Added Jim Woolner, partner in Beconta Inc., and a long-time officer and director of SIA, "Jim attended every SIA director's meeting, executive meeting and marketing meeting for all the years he was with us, and kept us out of trouble." Weinstein was still sharp as a tack at age 98, when he assisted in preparing a 50-year history of the national trade show.