Seven miles downstream and ten miles by road from the Knife River site, well signed off Hwy-200, Fort Clark State Historic Site (701/328-3508, daily May-Sept., free) is as eerily isolated as can be. One of three major fur-trading posts on the upper Missouri River, Fort Clark was founded by the American Fur Company circa 1831, primarily to trade with the Mandan people. The fort was visited by other Native Americans, as well as the usual list of adventurers, explorers, and frontier luminaries, such as Prince Maximilian, George Catlin, and Karl Bodmer; unfortunately, the steamboats that plied the waters to bring supplies also brought smallpox, and in one tragic winter in 1837, the Mandan people’s population was cut by 90 percent. After the fur trade declined, Fort Clark was abandoned in 1860.

Today the tranquil site, approached on a narrow gravel-and-dirt road, is devoid of anything—it’s a somber, quiet piece of history stretching out on a grassy flat-topped bluff overlooking the Missouri River. Unfortunately, the silence and emptiness of the place are marred by the presence of a smoky Basin Electric Power Company coal plant up the river. A walking trail has markers designating the locations of eight original buildings, and depressions from an earth lodge village and primitive fortifications are still apparent, but you need to use your imagination to see much.