The Communist Party USA (CPUSA) is a Marxist-Leninist political party in the United States, established in September 1919. It was formed from the left wing of the Socialist Party of America, specifically through the merger of the Communist Labor Party and the Communist Party of America. Historically, the CPUSA is known for its significant role in labor movements, its consistent opposition to fascism, and its long-standing alignment with the Soviet Union's Communist International (Comintern), of which it was a founding member. The party reached its peak membership of approximately 75,000 to 100,000 in the mid-1940s and faced periods of intense government repression, including the Palmer Raids in the 1920s and Smith Act prosecutions during the McCarthy era in the 1950s. Prominent historical figures associated with the party include William Z. Foster and Gus Hall. While its influence has diminished significantly, the CPUSA remains active today, advocating for socialism, civil rights, and anti-imperialism.