Northern Straits is a Salishan language within the Coast Salish branch. Among the Coast Salish languages, Northern Straits is one of the two languages in the Straits Salish branch, the other being Klallam. Klallam and Northern Straits are very closely related, but have lost mutual intelligibility.[2]
Historians have historically classified the various dialects of Northern Straits and Klallam together in many ways. Linguist George Gibbs, in 1863, classified Klallam, Sooke, and Songhees as being one language, Lummi, Saanich, and Semiahmoo being another language, and Samish being a dialect of another Coast Salish language, Lushootseed. One missionary, Myron Eells, believed that Lummi was a dialect of Klallam. German anthropologist Franz Boas believed that Klallam was part of the same language as Northern Straits. Furthermore, Charles Hill-Tout, a Canadian anthropologist, classified Sooke, Saanich, Songhees, Lummi, and Klallam as one language called "Lekonenen," and Songhees as another called "Lekunen." What Hill-Tout believed to be the names of the languages were actually derived from the words lək̓ʷəŋiʔnəŋ (the Songhees name for Songhees dialect) and lək̓ʷəŋən (the Songhees name for the Songhees people). Despite this, Klallam and the dialects of Northern Straits Salish are not mutually intelligible.[2]