Fort Union Trading Post National Historic Site is a partial reconstruction of the most important fur trading post on the upper Missouri, 1829-1867. The fort site is about two miles from the confluence of the Missouri River and its tributary, the Yellowstone River, on the North Dakota/Montana border, 25 miles from Williston, North Dakota.
The park is named Fort Union Trading Post by the National Park Service to differentiate it from Fort Union National Monument, a historic frontier Army post in New Mexico.
