The Louisiana Purchase Sesquicentennial half dollar was a proposed United States commemorative coin, legislation for which passed both houses of Congress, but was vetoed in 1954 by President Dwight Eisenhower. Intended to celebrate the 150th anniversary of the Louisiana Purchase (1803), the coin was lobbied for by both the Missouri Historical Society (MHS) and the Louisiana Purchase 150th Anniversary Association of New Orleans, who hoped to be able to buy the entire coin issue from the government and sell it at a profit.