San Juan Island is the second largest and most populous of the San Juan Islands. It has a land area of approximately 55 square miles. The 2000 census showed a population of 6,822.
Washington State Ferries serves Friday Harbor, which is San Juan Island's major population center, the San Juan County seat, and the only incorporated town in the islands.
The name "San Juan" comes from the 1791 expedition of Francisco de Eliza, who named the archipelago Isla y Archiepelago de San Juan to honor his patron, Juan Vicente de Güemes Padilla Horcasitas y Aguayo, 2nd Count of Revillagigedo. One of the officers under Eliza's command, Gonzalo López de Haro, was the first European to discover San Juan Island itself. The American explorer Charles Wilkes renamed the island Rodgers Island, but the Spanish name was kept on British charts and became the standard.
The only major commercial establishment outside of Friday Harbor is the village and resort of Roche Harbor on the northwest side of the island.
Other notable landmarks are the old British and American Camps at opposite ends of the island which together comprise the San Juan Island National Historical Park, which commemorates the 1859 "Pig War". Interpretive centers and reconstructed buildings, formal gardens, etc. recall the history of early European settlement in the area.
The University of Washington runs a marine research lab and campus outside of Friday harbor. The campus has been extant since 1909 and has dorms, food services and lecture classrooms.
