The river was named after the Methow Native Americans (today part of the Confederated Tribes of the Colville Indian Reservation). The name "Methow" comes from the Okanagan placename /mətxʷú/, meaning "sunflower (seeds)". The Native American name for the river was Buttlemuleemauch, meaning "salmon falls river". In 1841 the Wilkes Expedition named the river "Barrier River". Alexander Rosssaid the native name was Buttle-mule-emauch. In 1811 David Thompson met the tribe living along the river and wrote their name as Smeetheowe. In 1853 George Gibbs called the river Methow or Barrier.