Hidatsa /hɪˈdɑːtsə/ is an endangered Siouan language that is related to the Crow language. It is spoken by the Hidatsa tribe, primarily in North Dakota and South Dakota. A description of Hidatsa-Mandan culture, including a grammar and vocabulary of the language, was published in 1877 by Washington Matthews, a government physician who lived among the Hidatsa at the Fort Berthold Indian Reservation. More recently, the language has been the subject of work in the generative grammar tradition.