[1] The county seat and only incorporated town is Friday Harbor,[2] on San Juan Island.

The San Juan Islands were the subject of a territorial dispute between Great Britain and the United States from 1846 to 1872, leading to the Pig War in 1859.

The bloodless conflict ended through arbitration led by Kaiser Wilhelm I, which awarded the islands to the United States.

[5] San Juan County was home to Henry Cayou, one of the first elected officials of Native descent in Washington.

[6] On the 7th of June 2024, a T-34 plane flown by former astronaut and Air Force pilot William Anders crashed on the San Juan Islands.

San Juan County is a cluster of more than 400 islands and rocks with elevations above mean high tide.

The highest point in the county is Mount Constitution on Orcas Island at 2,407 feet (734 m) above sea level.

The four largest islands are: The county's population grew from around 4,000 in 1970 to nearly 19,000 by 2022, including a significant contingent of remote workers.

Due to high housing costs, San Juan County has the highest income inequality rate in Washington.

Waldron Island, with a population of 104 in the 2000 census, is considered one of the most impoverished areas in Washington, with about 56% of the people living in poverty.

[citation needed] In a survey by the University of Wisconsin Population Health Institute and the Robert Wood Johnson Foundation, San Juan County was ranked the healthiest in the state of Washington.

[22] The sheriff has a mutual aid agreement with the National Park Service Law Enforcement Rangers assigned to the San Juan Island National Historical Park and, in the event of an exigency, can also request assistance from the Washington State Patrol's District 7 field detachment.

[22][21][23][24] The county's first sheriff was Stephen Boyce, who was known among area Native Americans as Hyas Tyee ("great and powerful man" in the Coast Salish language).

The only area of the county won by George W. Bush in 2004 was the Decatur Island/Blakely Island precinct, with just over 50 votes.

In the first nine months under the policy, vacancies were filled faster and fewer sick days were used by employees.

[31] Due to high demand, vehicle spaces on the ferry runs generally require reservations during the summer months.