The Socialist Party of America (SPA) was a socialist political party in the United States. It was formed in 1901 by a merger between the three-year-old Social Democratic Party and a wing of the older Socialist Labor Party. It flourished in numerous ethnic enclaves from 1904 through 1912, with Eugene V. Debs as its presidential candidate. It splintered over World War I and Russia's 1917 October Revolution and was a minor political movement after 1920, often nominating Norman Thomas for president.