Fowke and Glazer 'Songs of Work and Protest' refer to quite a number. To cite a few:
Solidarity Forever - John Brown's Body which in turn was from 'Say Brother Will You Meet Us'
'Union Train' - 'The Old Ship of Zion' (this one?)
We Shall Not be Moved - I Shall Not be Moved
Casey Jones (trad) - Casey Jones - Union Scab (Joe Hill)
Roll the Union On - 'Roll the Chariot On'
Which Side Are You On - 'Lay Lily Low'/'Jack Munro'
'We Are Building a Strong Union' - We Are Climbing Jacob's Ladder
Dump the Bosses off Your Back - What a Friend we have in Jesus
There Is Power in the Union' -There Is Power in the Blood of the Lamb