It was founded in 1901 in Reading, Pennsylvania and received a state charter from the Socialist Party of America the following year.
Readings Socialists elected multiple state legislators, city councilors as well as mayor J. Henry Stump.
The Socialist Party of America nominated former Pennsylvania Representative and SPA member Darlington Hoopes for president in 1952 and 1956.
[1] The national party was renamed Social Democrats, USA in 1972.
A successor organization, the Socialist Party USA, was formed in 1973 by the Debs caucus of the old SPA, a group which still supported independent socialist political action.