In 1830-1831, James Kipp, an employee of American Fur Company, built Fort Clark Trading Post south of the Mandan village in hopes of enhancing trade with the Indians. The first steamboat to journey to the Upper Missouri, the Yellow Stone, arrived at Fort Clark in 1832. In June 1837 the steamboat St. Peters docked at Fort Clark carrying passengers infected with smallpox. Soon the disease swept through the Mandan village, killing about 90 percent of the inhabitants.

More than 2,200 surface features represent the ruins of houses, graves, storage pits, and other cultural remains. The 100 large, shallow doughnut-shaped earth lodge depressions are hard to see unless you walk near them.