Archibald McDonald’s was one of the most important fur traders in the region west of the Rockies. He is particularly remembered as a factor at Fort Langley, Kamloops, and Coivile and as one of the traders who enabled the Hudson’s Bay Company to gain control of the vast region west of the Rockies. His letters to friends, business colleagues, missionaries, botanists, and many others provide a fascinating narrative of the expansion of the fur trade in the Pacific Northwest at a critical time in its history.