History & Culture

Fort Union: The Briefest of Overviews

Black and white image of a man in formal 1800s suit sitting in a library setting
John Jacob Astor (1763-1848), founder of the American Fur Company. Astor's company built Fort Union near the Missouri and Yellowstone Rivers' confluence in 1828.

An 1864 black and white copper plate engraving of John Jacob Astor (FOUS 2818). NPS Photo.

On the spacious plains in 1828, near where the mighty Missouri and Yellowstone Rivers joined, John Jacob Astor's American Fur Company built what became its most famous fur trade post. Although called a fort, the post was neither a government nor a military installation, but a privately owned commercial establishment founded to engage in business with the Northern Plains Tribes. Built at the request of the Assiniboine nation, Fort Union Trading Post, then called Fort Union, quickly emerged as the Upper Missouri's most profitable fur trade post. This trade business continued until 1867, giving rise to a uniquely diverse, peaceful, and productive social and cultural environment that helped make Fort Union western America's longest-lasting fur trade post.

From 1828 to 1867, seven Upper Missouri tribesAssiniboine, Plains Cree, Blackfeet, Plains Chippewa, Mandan, Hidatsa and Arikiara—annually traded buffalo hides, beaver pelts, and other furs for hundreds of goods imported from eight countries. In exchange for furs that ranged from grizzly bear and bison to mice, tribal trading partners received manufactured materials such as calico cloth, guns and ammunition, clothing, pipes, beads, and cooking ware. On average, the post received more than 25,000 buffalo robes and sold more than $100,000 in merchandise each year. The post also provided federal Indian agents with a base of operations and storage warehouse before the national government established a permanent presence in the Trans-Mississippi West after the Civil War.

Foreground of landscape painting shows Assiniboine traveling through on horseback and foot though a valley twords Fort Union in center of painting, Missouri River in background.
"Fort Union on the Missouri" by Karl Bodmer, a Swiss artist who traveled up the Missouri River with Prince Maximilian of Wied in the summer of 1833. Sketches Bodmer made at the time of the fort and the Assiniboine people became the basis for this later print.

A lithographic print of "Fort Union on the Missouri" published circa 1843 (FOUS 2761). NPS Photo.

The Indian and fur trades weren't the only post activities that contributed to Fort Union's longevity and legacy. The American Fur Company and its successors routinely hosted well-known visitors during the fur trade period. George Catlin, Prince Maximilian of Wied, Karl Bodmer, and John James Audubon were but a few of the many artists and scientists who came to the Upper Missouri fort to learn about and document the region's native peoples, wildlife, and landscape. Their observations, recorded in sketches, paintings, and journals later shared with people in the East and overseas, made the region the most well documented in the American West prior to photography's widespread adoption.

By the 1860s, the Upper Missouri area these artists and scientists had visited was experiencing dynamic political and social change. Settlers moved west from the States, a migration that accelerated not long after the Dakota Territory was established in 1861. To protect at first the Missouri River, the major transportation corridor into the Northern Plains, and then the growing Euro-American settlements in the formerly tribal-controlled Upper Missouri region, the U.S. Army in 1866 built Fort Buford three miles east of the trade post. The next year, in 1867, the Army purchased Fort Union from its last private owner, the Northwest Fur Company. Soldiers dismantled the palisades and bastions and transported the salvaged timber and stone to the new Army post, where both were used for building materials. The crews of passing riverboats also scavenged what wood they could for firewood to feed steam engines powering the Missouri River's swelling steamboat traffic. Within a few years, little visible trace remained of the Upper Missouri's once-dominate commercial hub.

A century later, following decades of periodic attempts to preserve Fort Union's legacy, local citizens and historians launched a sustained campaign to preserve the historic fort site and rebuild the post. At their urging, the National Park Service acquired the site in 1966. Two years later, archaeological excavations commenced and continued into the early 1970s. Today's Fort Union is a reconstruction based in part on the archaeological evidence recovered during those and later excavations completed between 1986 and 1988. Rebuilt to its appearance in 1851, at the height of the Indian and fur trades, the fort offers a place that helps illuminate the Indian and fur trades'—and the post's—role in shaping the land and culture of the Upper Missouri region and the Northern Great Plains.

Three brown flint stone and three metal arrowheads.
Three each of the stone and metal arrowheads archaeologists discovered at Fort Union; they are now part of the park's museum collections. From top left, the catalog numbers are FOUS 49993, 3911, 99782, 16788 (iron), 97844 (cuprous), and 16794 (brass). The penny is shown to provide a sense of scale.


The Upper Missouri River peoples' adoption of metal arrowheads, or projectile points, is but one example of this cultural change discussed at the fort today. Before Europeans had arrived, the Assiniboine and other Northern Plains tribes manufactured stone arrowheads by knapping, or chipping, flakes from a stone core with a harder rock. The three stone arrowheads pictured at right (top row) were unearthed by archaeologists at Fort Union. All three were made from the strong and durable Knife River flint quarried 250 river miles to the post's east and later traded upriver. With Fort Union's construction, the post's traders introduced the Upper Missouri River peoples to new materials, technologies, and supplies; as their trading relationships grew, accelerating cultural exchange, the Assiniboine and their neighboring tribes increasingly purchased and used easy-to-make iron, brass, and cuprous projectile points like the ones also found and pictured here.
We invite you to explore this site further and discover the people, places, archaeological collections, and stories that illuminate the post's and the region's rich natural and cultural heritage. Detailed information about the fort's reconstruction and historic furnishings can be found on our Fort Union 50th Anniversary pages and in our Historic Furnishings Report. We also invite you to help us preserve and share these resources and stories.

Last updated: January 6, 2018

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