San Juan Island National Historical Park, National historic park in San Juan County, United States

San Juan Island National Historical Park covers 2,146 acres in two units: American Camp on the southern peninsula and English Camp on Garrison Bay in the northwest. American Camp holds three surviving buildings—two officers' quarters and the laundress's house—plus a prairie where the island marble butterfly lives. English Camp keeps its commissary, barracks, blockhouse and hospital.

The camps date from the Pig War, sparked in 1859 when an American settler shot a stray Hudson's Bay Company pig. Both sides garrisoned the island until 1872, when Kaiser Wilhelm I arbitrated the boundary as the Haro Strait, awarding the islands to the United States. The British withdrew, and the sites became a national park in 1966.

Coast Salish ancestors settled the island about 11,000 years ago as the ice shelf receded; shell middens in both camp areas mark villages predating Europeans. Smallpox reached the area by the 1770s and devastated the population. The Lummi Nation, among those tribes, is working to restart traditional uses of the English Camp area, including reef net fishing.

Both areas—American Camp and English Camp—are free to visit and each has an information center. The visitor centers provide guidance and background information on what you will see.

The Union Jack flies at English Camp, raised and lowered daily by National Park Service rangers. It is one of the very few places without diplomatic status where US government employees regularly hoist another country's flag. The camp sits on Garrison Bay, where the British garrison was posted from 1860 to 1872.