Tonasket is a city in Okanogan County, Washington, United States. The population was 994 at the 2000 census and increased 3.8% to 1,032 at the 2010 census.
Tonasket was officially incorporated on December 16, 1927. It is named after Chief Tonasket of the Okanogan people, a local leader from this area who assumed the status of grand chief of the American Okanogan after the drawing of the U.S.-Canada border by the Oregon Treaty of 1846, assuming a leadership role in Okanogan territory formerly held by Chief Nicola who lived north of the border.
Tonasket is a small community located along the eastern bank of the Okanogan River in north central Okanogan County, Washington. State Highway 97, the main north-south highway through central Washington, bisects the city on its way north to the Canadian border approximately twenty miles north. The city, with an elevation of approximately 900 feet above sea level, is bordered on the north by Siwash Creek, and the south by Bonaparte Creek. The present population is estimated to be approximately 995.