John Jacob Astor's American Fur Company built Fort Union Trading Post in 1828 near the junction of the Missouri and Yellowstone rivers in
what is now North Dakota. In its heyday, the post was a busy place and employed up to 100 people and all employees were furnished board and lodging free of charge. It became the headquarters for trading bison hides and other furs
with the Assiniboin Indians to the north, the Crow Indians on the upper Yellowstone and the Blackfeet who lived farther up the Missouri.