I found an old question (c. 1906) in the works of Werner Sombart, who was a radical Marxist activist and scholar. He wondered why socialism did not take root as widely or popularly in the U.S. compared to other Western/modern/industrialized/white ethnic countries. Imho, the question remains relevant, and I'd love to hear some of the latest thoughts from historians, U.S. and otherwise, regarding this quandary.
Further to OP's question: my understanding is U.S. trade unions did not accept socialisms call for revolution and instead pursued negotiations, strikes, etc. thus keeping workers mostly satisfied.
How much did trade unions play a part in staving off socialism in the U.S.?