Washburn is a city in McLean County, North Dakota in the United States. It is the county seat of McLean County. The population was 1,246 at the 2010 census. Washburn was founded in 1882 and became the county seat in 1883. Washburn is home to the North Dakota Lewis and Clark Interpretive Center which focuses on the Expedition's winter with the Mandans and houses a full-scale replication of Fort Mandan and one of the expedition's canoes.