The fort's commercial success created peace between the natives and the white settlers, and the fort became a beacon for scientists and artists who wanted to study and document the landscape and its residents. However, the increasing migration of Europeans into the area led to the construction of Fort Buford in 1866 by the U.S. Army, which purchased then dismantled Fort Union. The site was purchased in 1966 by the National Park Service, which rebuilt the fort using materials uncovered during archeological excavations as a blueprint for how the fort appeared.

This fortified site springs up from the sprawling North Dakota prairie, with rugged bluffs on its fringes. When you head here with a Williston rental camper, you can take a step through the fort's gates and experience this historic site nearly exactly as it was in the mid-1800s.