The Socialist Party of America (SPA) was a socialist political party in the United States formed in 1901 by a merger between the three-year-old Social Democratic Party of America and disaffected elements of the Socialist Labor Party of America who had split from the main organization in 1899.
In the first decades of the 20th century, the SPA drew significant support from many different groups, including trade unionists, progressive social reformers, populist farmers and immigrants. Eugene V. Debs twice won over 900,000 votes in presidential elections (1912 and 1920), while the party also elected two U.S. representatives (Victor L. Berger and Meyer London), dozens of state legislators, more than 100 mayors, and countless lesser officials.