Ashland, Oregon

The Oregon-California border sits on the 42nd parallel, and this line was set by a treaty between the United States and Spain in 1819, decades before either Oregon or California were states, and before the U.S. even controlled the territory. The Adams-Onis Treaty was signed on February 22, 1819, by Secretary of State John Quincy Adams and Spanish Minister Luis de Onis. Spain ceded Florida to the United States. In return, the U.S. renounced its claims to Texas. The treaty also drew a line across the entire continent. That line followed the Sabine River westward, then ran north to the 42nd parallel, then west along the 42nd parallel to the Pacific Ocean. Everything north was American sphere. Everything south was Spanish. Spain was saying: Oregon Country is yours, California is ours. When Mexico won independence from Spain in 1821, it inherited the same boundary. When the U.S. acquired California from Mexico in 1848 and organized Oregon Territory that same year, the old Adams-Onis line simply became the border between two American territories. It persists to this day. A line drawn to settle a dispute with a colonial empire that no longer exists still determines whether you pay Oregon income tax or California income tax.