The great trading house of the upper Missouri, rebuilt on the ground where it stood.
Photo: Victoria Stauffenberg · Public domain · via Wikimedia Commons
For nearly forty years, this whitewashed post near the confluence of the Missouri and Yellowstone rivers was the most important fur trade center on the upper Missouri. John Jacob Astor's American Fur Company built it in 1828, at the invitation of the Assiniboine and on their territory, and around ten Northern Plains nations traded here — Assiniboine, Crow, Plains Cree, Blackfeet, Plains Ojibwa, Mandan, Hidatsa, Arikara, Lakota, and Dakota. In a good year more than 25,000 buffalo robes moved through the gates, exchanged for calico, guns and ammunition, blankets, beads, pipes, and cooking goods hauled upriver by steamboat. It was never a military fort. It was a business, and its business was the relationship between the Plains nations and a global market.
Be clear about what you are walking into: the fort you see is a reconstruction, not a survivor. The Army bought the post in 1867 and dismantled it, hauling the timber and stone downriver to build Fort Buford, and steamboat crews scavenged what was left for fuel. The National Park Service acquired the site in 1966, excavated it archeologically between 1968 and 1972 and again from 1986 to 1988, and rebuilt on the original footprint using those findings alongside period drawings, inventories, and travelers' accounts. What stands today is deliberately a partial reconstruction, set to the fort's appearance in 1851 at the height of the buffalo robe trade — the palisade, the two stone bastions, the whitewashed Bourgeois House, and the Indian Trade House just inside the gates. The Park Service left it intentionally incomplete rather than pretending to a certainty the record does not support.
The site straddles the North Dakota–Montana line, which is a small pleasure of its own: the state boundary marker sits a few hundred feet west of the fort walls. It is about 25 miles southwest of Williston, North Dakota, and about 24 miles northeast of Sidney, Montana, on ND Highway 1804. There is no fee. Ninety minutes to two hours does it justice, and it makes an easy northern bookend to a Theodore Roosevelt National Park run.
Whitewashed palisade walls, two stone bastions at opposing corners, and the Bourgeois House at the center — all rebuilt on the original site from archeological excavation and period documents, set to the fort's 1851 appearance. The reconstruction is intentionally partial, and the Park Service says so plainly rather than filling gaps with guesswork.
Insider tipThe whitewash is not a modern flourish. The post's manager believed a bright white fort visible from a distance would draw more trade, and the record supports it.
Plan a trip to this spot →The clerk-in-charge's house — the bourgeois, in the trade's French vocabulary — doubles as the visitor center and museum, with exhibits on the fur trade economy, the Plains nations who traded here, the archeology behind the reconstruction, and the artists and travelers who passed through. Karl Bodmer, George Catlin, and John James Audubon all came up the Missouri to this post.
Insider tipStart here. The reconstruction outside makes far more sense once you have seen the excavation evidence it was built from.
The small room where the actual exchange happened, stocked with reproduction trade goods. Interpreters here walk you through how a trade was negotiated, what a buffalo robe was worth in blankets or powder, and how the credit system bound the post and the tribes together season after season.
Insider tipStaffed seasonally, roughly Memorial Day through Labor Day. Outside that window you can see the room but not the interpretation, which is most of the value.
A short walk of about 2,000 feet round trip drops off the fort terrace into cottonwood bottomland toward the Missouri. It is the quickest way to understand why the post was sited exactly here — steamboat access, timber, and a river that was the only practical highway into this country.
Insider tipThis is prime mosquito habitat in summer. Repellent before you start, not after.
The site sits on both sides of the border, and the boundary sign stands within easy walking distance of the palisade. A photograph with one foot in each state is an unserious pleasure, and everyone takes it anyway.
Insider tipKeep your watch on Central time regardless of which side you are standing on — the park runs on Central even though Montana generally does not.
Plan a trip to this spot →One entrance off ND Highway 1804 — free, and the grounds are open daily.
From Williston, take US-2 west to ND-1804, turn left and run about 20 miles, then turn right to stay on 1804; the entrance road is on the left about 2 miles on. From Sidney, MT, take MT-200 northeast about 11 miles to the roundabout, take the third exit north onto ND-58 for about 10 miles, then turn left onto ND-1804 with the entrance about 2 miles ahead on the left. No entrance fee and no pass required. The west lot handles buses and RVs; the east lot is closer to the fort and has accessible parking. Published hours have varied between sources and seasons — confirm on nps.gov/fous or by calling the park before you build a schedule around them.
No lodging, camping, food, or fuel at the site — base in Williston or Sidney.
About 25 miles northeast and the larger of the two gateways, with the widest choice of chain and independent lodging, restaurants, groceries, and fuel. Also has commercial air service, rental cars, and an Amtrak Empire Builder stop.
Booking tipThe practical base if you are working a Missouri River route east toward Theodore Roosevelt's North Unit.
About 24 miles southwest across the state line, a smaller town with a modest set of motels, restaurants, and services. Convenient if you are coming up from the Montana side or continuing west.
Booking tipFewer rooms than Williston — worth booking ahead, especially around Rendezvous weekend in June.
South of Williston on US-85 and the gateway to Theodore Roosevelt National Park's North Unit. A reasonable overnight if you are pairing Fort Union with the badlands the next morning.
Booking tipRegional lodging fills unpredictably with energy-sector work traffic. Reserve rather than rolling in and hoping.
Is the fort original?
No. The original post was dismantled by the Army in 1867 and its materials hauled off to build Fort Buford. What stands today is a partial reconstruction built by the National Park Service on the original site, based on archeological excavations from 1968–1972 and 1986–1988 together with period drawings and documents, and set to the fort's 1851 appearance. The Park Service deliberately left the reconstruction incomplete rather than invent what the evidence does not show.
Is there an entrance fee?
No. Fort Union Trading Post National Historic Site is free and no entrance pass is required.
How long should I allow?
About an hour and a half to two hours covers the Bourgeois House museum, the Trade House, the fort grounds, and the short river bottom walk. Add time if you catch a living history program or arrive during Rendezvous.
Was this a military fort?
No. It was a privately owned commercial trading post run by the American Fur Company, built on Assiniboine land at their invitation. The only military presence was a brief occupation in 1864–1865, near the end of its life.
Which nations traded here?
The Assiniboine were the primary trading partners, with roughly ten Northern Plains nations doing business at the post overall — Assiniboine, Crow, Plains Cree, Blackfeet, Plains Ojibwa, Mandan, Hidatsa, Arikara, Lakota, and Dakota.
What time zone is the park on?
Central. This catches people out, because the site straddles the state line and Montana is otherwise on Mountain time. If you are arriving from Sidney, you lose an hour.
Are there services on site?
No fuel, food, or lodging at the site. Arrive fueled and carry water. The nearest full services are in Williston, ND and Sidney, MT, roughly 25 minutes away in either direction.
When is the Rendezvous?
The annual Fort Union Rendezvous is held on the third weekend of June, with free admission and parking. Expect fur trade era reenactors, trade negotiation demonstrations, blacksmithing, spinning and weaving, pottery, and frontier cooking. The Indian Arts Showcase follows on the first weekend of August. Confirm dates on nps.gov/fous, as they shift year to year.
Do I need insect repellent?
Yes, especially from late spring through summer. The park's own rangers list it among their top visiting tips — the Missouri bottomland produces mosquitoes in numbers that travelers were writing about nearly two centuries ago.
Pick your vehicle, line up the stops on the way in and out, and carry the whole route in your pocket.
