Kohnstamm assumed management of the Depression-era Timberline Lodge in the early '50s, after it had been closed for more than a decade. He installed chairlifts and launched the first lift-served summer skiing in the U.S. He later convinced the federal government to construct the Wy'East Day Lodge to spare Timberline from the daily toll of skier traffic. Timberline, built as a public works project in 1937, is now a National Historic Landmark.
In 1992, Kohnstamm's contributions to the growth of the sport and creation of a resort icon led to his induction into the U.S. National Ski Hall of Fame and Museum in Ishpeming, Mich.
Kohnstamm is survived by his wife, Molly; sons, Jeff, John, Kevin and David; and 10 grandchildren.