John Adams Dix (July 24, 1798 – April 21, 1879) was an American politician and military officer who was Secretary of the Treasury, Governor of New York and Union major general during the Civil War. He was notable for arresting the pro-Southern Maryland General Assembly, preventing that divided border state from seceding, and for arranging a system for prisoner exchange via the Dix–Hill Cartel, concluded in partnership with Confederate Major General Daniel Harvey Hill.