Missouri

originally a name for a group of native peoples among Chiwere (Siouan) tribes, from an Algonquian word recorded c. 1700, said to mean literally "people of the big canoes." Formed as a U.S. territory in 1812 (out of the whole of the Louisiana Purchase not admitted that year as the state of Louisiana); admitted as a state 1821.

In U.S. history, the Missouri Compromise (1820) in Congress admitted Missouri as a slave state, along with Maine as a free one, but set a line westward from the main southern boundary of Missouri above which no new states would be admitted with slavery. It has been the Show-Me State since at least 1902; the expression I'm from Missouri, you'll have to show me is attested from at least c. 1880. Related: Missourian.