William Leuchtenburg in The Perils of Prosperity speaks a bit on this subject but not in thorough depth.

*The Soviet leaders such as Lenin thought Samuels Gompers,"head of the AFL, as merely an 'agent of the bourgeoisie'." However Gompers hoped to align more with Leninist Socialism.

*Militant organized labor outfits began to grow in 1919. It was hard for the common middle-class American to separate the strikers from radical socialist. 1919 alone saw "four million workers walk[ing] out of their jobs." Since many Americans were not used to such drastic amounts of strikes, which were trying to keep up with postwar inflation, the connection of socialism to unpopular strikes such as the Seattle General Strike became popular opinion. Leuchtenburg goes into detail about the violence in Seattle with home-made bomb explosions having female targets which stirred the pot.

*Sacco and Vanzetti would be the boiling point when immigrants + murder + accused Socialist beliefs = All socialist are immigrants or immigrant sympathizers.