Heintzleman was made head of the National Recovery Administration forest conservation efforts in 1934. In 1937, he was appointed Alaskan Representative of the Federal Power Commission. The same year he was promoted to Regional Forester for Alaska, a post he held till 1953. As Regional Forester he also held the position of Alaskan Commissioner of the United States Department of Agriculture. In this role he encouraged the development of lumber and pulp mills along with other industrial development. From 1939 to 1940 he served as chairman of the Alaska Territorial Planning Board.