Mandan (mănˈdăn, –dən) [key], city (1990 pop. 15,177), seat of Morton co., S N.Dak., on the Missouri River opposite Bismarck; inc. 1881. A railroad division point, it is the distribution center for a grain, livestock, and dairy region. The city has a large cattle market and food-processing plants. Manufactures include wood and metal products and tile. Lewis and Clark wintered there (1804–5) in the Mandan Native American villages. A state industrial school is in the city, and a U.S. agricultural experiment station is nearby.