Donald Hathaway Clark was born in Chicago, Illinois on August 5, 1890 to John Henry and Catherine (Little) Clark. He moved to Oregon at the age of eighteen, then to Seattle where he received his B.S. degree (1916), M.S.F degree (1917), and Ph.D. degree (1952) in Forestry from the University of Washington. Clark married Mildred Margaret Taylor on June 20, 1921 and settled in Lawtonwood, Washington until his death on June 18, 1965.

Donald Clark began his career as secretary and manager of the Red Cedar Shingle Assocation (1919-1923), then left to become the owner and manager of Cascade Cedar Co. between 1923 and 1936. Clark was the sales manager for Colonial Cedar Co. from 1936 to 1942, at which point he left for service as a Captain in Air Combat Intelligence in the Pacific theatre of operations during World War Two. When he returned, he took a position at the University of Washington as a research associate working with forest products in the College of Forestry from 1945 until 1953. He then served as director of the Institute of Forest Products until he retired from the University in October 1960.

Donald Clark authored numerous magazine and newpaper articles, as well as published books, such as (1949) and (1952) during his career. After his retirement, he continued to research in the field of forest products as a consultant to the Red Cedar Shingle Bureau and secretary and manager of the Northwest Hardwood Association. As a result of his writings and influence, the industry became aware of the potential commercial uses of native hardwood timber, such as the native Red Alder, and the leaders in the hardwoods industry decided to form the Northwest Hardwood Association. Clark also continued to lecture throughout the Pacific Northwest on ghost towns, Washington place names, and canon hunting, as well as serving a member in the Washington State Historical Society, Forest History Society, and dozens of other local and regional organizations.