Pig War: Ambiguity in the Oregon Treaty leads to the "Northwestern Boundary Dispute" between United States and British/Canadian settlers.

The Pig War was a confrontation in 1859 between the United States and the United Kingdom over the British–U.S. border in the San Juan Islands, between Vancouver Island (present-day Canada) and the State of Washington. The Pig War, so called because it was triggered by the shooting of a pig, is also called the Pig Episode, the Pig and Potato War, the San Juan Boundary Dispute and the Northwestern Boundary Dispute. Despite being referred to as a war, there were no casualties on either side.