Fort Clark State Historic Site preserves records of the early fur trade in North Dakota and remembers the personal tragedy of devastating smallpox and cholera epidemics.  The fort was built as a trading post in 1830-1831, south of  the Mandan village of Mitu’tahakto’s, built in 1822 on the Missouri River at the confluence of Chardon Creek and Clark’s Creek.  Steamboat traffic was important to this fort economically, but it also carried disease—a smallpox outbreak in 1837 and in 1851 an outbreak of cholera.  Today, Fort Clark is on the National Register of Historic Places and has been nominated as a National Historic Landmark.  It has more than 2,200 surface features that represent the ruins of houses, graves, and other cultural remains.  The fort is open seasonally, from May to September, and has no admission fees, although donations are welcome.