Washburn was noted for his exploits in four areas. First, 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). Second, 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.

Third, he was responsible for some of the finest maps ever made of mountain regions; his map of Mount McKinley and his map of Mount Everest are perhaps the most notable, although his map of the Presidential Range in New Hampshire was closer to home. Fourth, and not least, his stewardship of the Boston Museum of Science made it into a first-class museum.

It is especially remarkable to note that some of these achievements – in particular the Everest map and subsequent further work on the elevation and geology of Everest – were carried out in his 70s and 80s.