John Jacob Astor's American Fur Company built Ft. Union Trading Post in 1828 near the junction of the Missouri River
and Yellowstone River in what is now western North Dakota.
In its heyday, the post was a busy place and employed up to 100 people and all employees were funished 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.
The trading post was partially reconstructed from 1986 to 1989 with structures appearing as they did in 1850-1851.