Social Democratic Federation (United States)
The Social Democratic Federation of the United States of America (SDF) was a political party in the United States, formed in 1936 by the so-called "Old Guard" faction of the Socialist Party of America. The SDF later merged again with the Socialist Party in 1957 to form the Socialist Party-Social Democratic Federation (SP-SDF).
Social Democratic Federation dues stamps were applied continuously to regular SPA dues booklets in 1936 & 1937.
Norman Thomas (circa 1937)
The Socialist Party of New York issued its own dues stamps for several months during the first half of 1936.
Louis Waldman, c. 1944
Socialist Party of America
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.
Election poster for Eugene V. Debs, Socialist Party of America candidate for President, 1904
Debs was the founding member of the Socialist Party of America.
Executive Secretary Adolph Germer was one of top five Socialist of America leaders prosecuted by the Department of Justice in 1919.
Alfred Wagenknecht, top leader of the 1919 Left Wing Section of the Socialist Party