Northern Prairie Wildlife Research Center
In just 16 short years (1792-1808) beaver populations surrounding the Pembina post became so depleted that it was closed. Lewis and Clark found beaver abundant along the Missouri River, particularly above the mouth of the Little Missouri River. Fur traders quickly followed Lewis and Clark up the Missouri River in search of the wealth beaver could provide. By the late 1820s and early 1830s the beaver trade had reached its peak in North Dakota. As many as 25,000 beaver were brought into Fort Union, near present-day Williston, in 1833.
It is striking how quickly the beaver fur trade, the driving force that opened the West, had passed. By 1839, no beaver were traded at Fort Clark, near present-day Washburn, and only scattered populations remained in the state. Beaver remained scarce until after 1900. Between 1910 and 1920 beaver colonies started to reappear on the Missouri River and its major tributaries and numbers continued to build during the 1930s and 1940s. During the early 1950s the number of beaver harvested dramatically increased. Today beaver are once again found in most of the streams and river systems capable of supporting a colony.