Washburn is especially noted for exploits in four areas.
He was one of the leading American mountaineers in the 1920s through the 1950s, putting up first ascents and new routes on many major Alaskan peaks (often with his wife, Barbara Washburn, one of the pioneers among female mountaineers and the first woman to summit Denali/Mt. McKinley).
He pioneered the use of aerial photography in the analysis of mountains and in planning mountaineering expeditions. His thousands of striking black-and-white photos, mostly of Alaskan peaks and glaciers, are known for their wealth of informative detail and their artistry. They are the reference standard for route photos of Alaskan climbs.
He was responsible for creating maps of various mountain ranges, including Mount McKinley, Mount Everest, and the Presidential Range in New Hampshire.
His stewardship of the Boston Museum of Science.