The Long Island Museum of American Art, History, and Carriages, informally known as the Long Island Museum, is an open-air museum located in Stony Brook, New York. Founded in 1939 as the Museums at Stony Brook, it changed its name in 2000. It is known for its collection of over 200 carriages and its extensive collection of work by the Hudson River School painter William Sidney Mount and over 4000 other paintings, sculptures and prints. In 2006, it became a Smithsonian affiliate.