evidence: I’ll leave it to future historians to puzzle out the reasons why, but in the second decade of the 21st century, in the unlikely setting of the most thoroughly capitalist country in world history, large numbers of Americans, mostly young, displayed a new interest in socialist ideas, values and policy proposals, and in turn in the often neglected history of socialism and communism in the United States. [...] But in 2020 an editor at a New York publishing house, noticing the upswing in interest among young Americans in leftwing (although non-communist) politicians like Bernie Sanders and Alexandria Ocasio-Cortez, contacted me wondering if there might be a readership emerging for a new narrative history of the Communist party USA, from its founding in 1919 to the demise of the Soviet Union in 1991.