The reservation was created by the Point Elliott Treaty of 1855. An executive order of September 9, 1873 clarified the northern boundary and added 59.73 acres establishing the 7,448.80-acre reservation. The people were influenced by Roman Catholic missionaries. Many of the people moved around various areas in Puget Sound seeking employment. They came into conflict with white settlers because of land. In 1884 three quarters of Indians on the reservation were engaged in farming, logging, and milling.
The Swinomish voted to accept the Indian Reorganization Act on November 16, 1935. The constitution was adopted and the governing body is the Swinomish Indian Senate. The tribe filed a claim for an alteration in its reservation. They want it as promised to them in the Point Elliott Treaty of 1855. On June 21, 1971 Indian Claims Commission ordered that the petition be dismissed.