The Lewis and Clark Expedition (1804–1806) crossed the Rocky Mountains and returned with detailed geographic and natural history information. Their reports helped convince traders and investors that the trans-Mississippi West held valuable resources, including beaver. This knowledge lowered uncertainty for later fur-trade expeditions into the Rockies.
John Jacob Astor founded the American Fur Company in 1808, building a large, organized business aimed at controlling key parts of the U.S. fur trade. The company’s size and capital helped push fur trading farther west by financing posts, supply chains, and partnerships. Its growing reach later intensified competition in the Rocky Mountain region.
In 1810, Astor created the Pacific Fur Company to expand the fur trade to the Pacific Northwest and link inland trapping to global markets. This move showed how valuable beaver pelts had become in international trade, especially for hat-making felt. It also increased rivalry between U.S. and British-Canadian fur interests across the northern Rockies and Columbia Basin.
In 1811, the Pacific Fur Company established Fort Astoria at the mouth of the Columbia River as a regional depot for collecting inland furs, especially beaver pelts. The post helped tie Rocky Mountain and interior trapping to coastal shipping routes. It also made the fur trade part of a larger contest over influence in the Pacific Northwest.
The Treaty of 1818 set the U.S.–British boundary in parts of the north and allowed “joint occupation” of the Oregon Country. That legal arrangement shaped where and how British-Canadian and American traders operated, especially along routes feeding the Rocky Mountains and Columbia Basin. In practice, it kept the fur trade international and competitive across the region.
In 1821, the Hudson’s Bay Company (HBC) and the North West Company merged under British government pressure, ending a violent rivalry in the Canadian fur trade. The merger created a stronger, more centralized competitor for American firms and independent trappers in western North America. This consolidation helped HBC organize large brigades that pushed into Rocky Mountain and Snake River trapping grounds.
In 1822, William H. Ashley and Andrew Henry formed what became known as the Rocky Mountain Fur Company in St. Louis. Instead of relying mainly on fixed trading posts, they recruited “Ashley’s Hundred” to trap directly in the mountains and bring pelts to trade. This shift helped define the “mountain man” era in the central Rockies.
Beginning in 1824, HBC officer Peter Skene Ogden led multiple expeditions into the Snake River country to trap heavily and reduce beaver populations. This approach—sometimes described as creating a “fur desert”—aimed to deny American rivals profitable trapping grounds. Ogden’s journals also show the difficult conditions of winter trapping and the limits of the resource base.
In early July 1825, trappers and traders met on Henrys Fork (near present-day McKinnon, Wyoming) for what is widely described as the first Rocky Mountain Rendezvous. The rendezvous system let companies bring supplies to a planned meeting place, then carry out furs without building many permanent posts. This greatly increased trapping activity across the Rockies by making remote work more practical.
In 1828, Astor’s American Fur Company established Fort Union near the confluence of the Missouri and Yellowstone Rivers. The post became a major commercial hub for trading with Northern Plains tribes and moving furs through the Missouri River corridor. Fort Union helped connect Rocky Mountain and northern plains fur flows to eastern markets with greater scale and efficiency.
In 1832, Fort Union received a steamboat, lowering transportation costs and speeding the movement of goods and furs along the Missouri River. This logistical change strengthened the American Fur Company’s ability to compete by resupplying faster and paying more for pelts. It also tied the remote fur economy more closely to industrial transport and cash credit networks.
In July 1832, after the rendezvous at Pierre’s Hole (in today’s eastern Idaho), fur trappers and a large group of Gros Ventre (A’aninin) people clashed in what became known as the Battle of Pierre’s Hole. The fighting highlighted how crowded and tense the Rockies had become as companies, independent trappers, and Native nations competed and tried to travel safely. It also showed that the fur boom brought not only trade, but higher risks of violence on key routes.
By the late 1830s, beaver in heavily trapped areas were becoming scarce, and hat styles shifted toward silk, reducing demand for beaver felt. As prices fell, the economics that had supported long, dangerous Rocky Mountain trapping trips weakened. Many traders and trappers began to pivot toward other products, such as buffalo robes and smaller furs.
The final Rocky Mountain Rendezvous took place in 1840, closing the annual system that had organized much of the mountain fur trade since 1825. Its end reflected both environmental limits (fewer beaver in many trapping grounds) and market change (less demand for beaver hats). By this point, the “mountain man” fur boom that had shaped the Rockies in the early 1800s was giving way to new western economies and settlement pressures.
Fur trade and Mountain Men in the Rocky Mountains (1800–1840)