Short answers, pulled from the story.
The Communist Party USA emerged from the left wing of the Socialist Party of America in 1919. By August 1919, only months after its founding, the party claimed between 50,000 and 60,000 members.
In 1949, the federal government put Eugene Dennis, William Z. Foster, and ten other Communist Party leaders on trial for advocating the violent overthrow of the government. All remaining eleven defendants were found guilty and the Supreme Court upheld their convictions by a 6 to 2 vote in Dennis v. United States.
Starting with $75,000 in 1959, the Soviet subsidies increased gradually to $3 million in 1987. There is at least one receipt signed by Gus Hall in the KGB archives confirming these payments.
Rosa Parks emerged as a prominent member of the civil rights movement after being organized by young activists from the Alabama chapter. James Ford, Charlene Mitchell, Angela Davis, and Jarvis Tyner all ran as presidential or vice presidential candidates on the party ticket while W.E.B. Du Bois, Paul Robeson, and Gwendolyn Brooks were one-time members or supporters.
On the 7th of April 2021, the party announced intentions to run candidates again after over thirty years of hiatus. In 2025, the party increased electoral activity fielding candidates for city council in Ithaca and Northampton.