 Lisa 's men started construction of Fort Raymond , which sat on a bluff overlooking the confluence of the Yellowstone and Bighorn , in the fall of 1807 . The fort would serve primarily as a trading post for bartering with the Native Americans for furs . This method was unlike that of the Pacific Northwest fur trade , which involved trappers hired by the various fur enterprises , namely Hudson 's Bay . Fort Raymond was later replaced by Fort Lisa at the confluence of the Missouri and Yellowstone in North Dakota ; a second fort also called Fort Lisa was built downstream on the Missouri River in Nebraska . In 1809 the St. Louis Missouri Fur Company was founded by Lisa in conjunction with William Clark and Pierre Choteau , among others . In 1828 , the American Fur Company founded Fort Union at the confluence of the Missouri and Yellowstone Rivers . Fort Union gradually became the main headquarters for the fur trade in the upper Missouri basin . 
 Lisa <a href='null_genetive' title='1'><mark>'s</mark></a>men started construction of Fort Raymond , which sat on a bluff overlooking the confluence of the Yellowstone and Bighorn , in the fall of 1807 . The fort would serve primarily as a trading post for bartering with the Native Americans for furs . This method was unlike that of the Pacific Northwest fur trade , which involved trappers hired by the various fur enterprises , namely Hudson <a href='null_genetive' title='2'><mark>'s</mark></a>Bay . Fort Raymond was later replaced by Fort Lisa at the confluence of the Missouri and Yellowstone in North Dakota ; a second fort also called Fort Lisa was built downstream on the Missouri River in Nebraska . In 1809 the St. Louis Missouri Fur Company was founded by Lisa in conjunction with William Clark and Pierre Choteau , among others . In 1828 , the American Fur Company founded Fort Union at the confluence of the Missouri and Yellowstone Rivers . Fort Union gradually became the main headquarters for the fur trade in the upper Missouri basin . 
Lisa  men started construction of Fort Raymond , which sat on a bluff overlooking da confluence of the Yellowstone and Bighorn , in tdafall of 1807 . The fort would serve primarily as a trading post for bartering wit thdaative Americans fir furs . This method was unlike dat of the Pacific Northwest fur trade , which involved trappers hired by thedarious fur enterprises , namely Hudson  Bay . Fort Raymond was later replaced by Fort Lisa at the dafluence of the Mdaouri and Yellowstone in North Dakota ; a second fort also called Fort Lisa was built downstream on the Missouri River in Nebraska . In 1809 the St. Louis Missouri Fur Company was founded by Lisa in conjunction with William Clark and Pierre Choteau , among others . In 1828 , the Amdacan Fur Company founded Fort Union at the confluence of the Missouri and Yellowstone Rivers . Fort Union gradually became the main headquarters fa the fur trade in the upper Missouri basin .