a major division of the Sioux (q.v.), or Dakota, confederation of American Indians.

city, seat (1862) of Yankton county, southeastern South Dakota, U.S. The city lies along the Missouri River near its confluence with the James River, on the Nebraska border, about 60 miles (100 km) southwest of Sioux Falls. Yankton is just east of Gavins Point Dam and Lewis and Clark Lake. Sioux Indians of the Yankton division (for whom the city is named) inhabited the area and held a council with Meriwether Lewis (Lewis, Meriwether) and William Clark (Clark, William) during their 1804–06 expedition. Settlement began in 1858, and the town site was laid out the following year. A fort was built in 1862. Yankton became a transportation centre, first with steamboats on the Missouri and later with the arrival of the railroad (1873). It served as the first capital of Dakota Territory (1861–83). The old Territorial Legislative Council Building is now part of the Dakota Territorial Museum. There is also a replica of the first territorial capitol building. Yankton is a regional business, health care, and recreation centre. Manufacturing is a major part of the economy; city industries produce aluminum products, electronics, construction equipment, livestock trailers, tarpaulins, engine filters, aircraft parts, and agricultural equipment. Area agriculture includes soybeans, corn (maize), and livestock; beef processing is also important. Yankton is the seat of Mount Marty College (1936). Gavins Point National Fish Hatchery and Aquarium is near the dam. Outdoor recreation activities are popular on the lake and at the nearby Lewis and Clark, Chief White Crane, and Pierson Ranch recreation areas. Yankton is located on the Lewis and Clark National Historic Trail. Inc. 1869. Pop. (1990) 12,703; (2000) 13,528.