American Political Party
By August 1919, only months after its founding, the CPUSA had 60,000 members, including anarchists and other radical leftists, while the more moderate Socialist Party of America had only 40,000 members. The sections of the CP's International Workers Order meanwhile organized for Communism around linguistic and ethnic lines, providing mutual aid and tailored cultural activities to an IWO membership which peaked at 200,000.
The CP's early labor and organizing successes did not last. As the decades progressed, the combined effects of the second Red Scare, McCarthyism, Nikita Khrushchev's 1956 Secret Speech denouncing the previous decades of Joseph Stalin's rule, and the adversities of the continued Cold War mentality steadily weakened the CPUSA. The American party's membership in the Comintern and its close adherence to the political positions of the Soviet Union enabled anti-Communist critics to constantly present the party as not only a threatening, subversive domestic entity, but also as a "foreign" agent fundamentally alien to the "American way of life." Internal and external crises swirled together, to the point where members who did not end up in prison for party activities tended either to disappear quietly from its ranks or to adopt more moderate political positions at odds with the CPUSA's party line. By 1957, membership had dwindled to less than 10,000, of whom some 1,500 were FBI informants.