Oto (ōˈtō) [key], Native North Americans, also called the Otoe, whose language belongs to the Siouan branch of the Hokan-Siouan linguistic stock (see Native American languages). The Oto had a Plains area type of culture. At one time, with the Iowa and the Missouri, they formed part of the Winnebago nation, N of the Great Lakes. The Oto with the Missouri left the nation, but after a quarrel the Oto separated from the Missouri and settled in S Minnesota. Constantly beset by overpowering enemies, they were driven south and joined the Pawnee near the mouth of the Platte River. In 1880–82 the Oto migrated to Oklahoma, where they once again live with the Missouri. In 1990 there were some 1,800 Oto-Missouri in the United States.
See B. B. Chapman, The Otoes and the Missourias (1965).