The SPUSA elected a couple of Congressmen and unsuccessfully ran Debs then Norman Thomas for President.  Their largest vote total was received prior to World War I.  Resistance to the US involvement in WW I, the Palmer Red Raids, and internal split on Bolshevik Revolution reduced them to insignificance as a party.

The CIO's history is interesting.  Their basic organizing principle, industrial unionism, was an IWW principle and the use of Sit Down Strikes was a Syndicalist tactic also touted by the IWW.  

Meany was the head of the AFL during the 50s and of the reunited AFL-CIO from mid 50s to 1979.

Ever since I learnt about confirmation bias I've started seeing it everywhere