By the second decade of the nineteenth century, the Hudson's Bay Company (HBC) had become a dominant presence in northwestern Montana, bartering trade goods for furs with the Kootenai, Pend d'Oreille, and Salish People. In 1812, the company built a trading post on the Clark Fork River near the mouth of Thompson River.The HBC relocated the post to a more accessible site very near here by the early 1820s. The trading post consisted of two dwellings, a store, and a horse corral. For over twenty years, Flathead House was an important trading post along the lower Clark Fork River. The establishment of the 49th parallel as the international boundary between the United States and Great Britain in 1846 caused the British to close Flathead House in 1847.

Famed American mountain man Jedediah Smith and seven companions unexpectedly showed up at Flathead House in November 1824. Under the leadership of John McLoughlin had HBC had worked for years to keep American fur trappers out to the Oregon country west of the continental divide. Company manager Peter Skene Ogden called Smith's arrival "that damn'd all cursed day." His appearance at the remote trading post signaled the beginning of the end of an HBC policy that had stripped much of western Montana of its beaver in a effort to keep the Americans out of the territory.

Erected by Montana Department of Transportation.