Here's the lyrics to Union Train:

UNION TRAIN (Lee Hays/Almanac Singers)

Oh, what is that I see yonder coming, coming, coming
Oh, what is that I see yonder coming, coming, coming
What is that I see yonder coming, coming, coming
Get on board! Get on board!

It's that union train a-coming, coming, coming (3)
Get on board! Get on board!

It has saved a-many a thousand, thousand, thousand (3)
Get on board! Get on board!

It will carry us to freedom, freedom, freedom (3)
Get on board! Get on board!

What is that I see yonder coming, coming, coming
Get on board! Get on board!

It's that union train a-coming, coming, coming (3)
Get on board! Get on board!

Copyright People's Songs Inc 1947.

Inspired by Southern Tenant Farmers Union organising sharecroppers and farm labourers in the cotton country of the Mississippi Delta. Many of them were black workers who sang their childhood hymns at union meetings. At a meeting in Memphis, after they had sung 'The Old Ship of Zion', a woman sang a new verse to the tune. Later, Lee Hays added more verses and the 'Union Train' began to roll. [Paraphrase of note by Fowke and Glazer].

I found an 'Old Ship of Zion' at the shape note site, but I doubt if it's the right one.

--Stewie.