I am skeptical about the theory that our Puritan influence somehow culled superstition from folk songs as they travelled to the new world. Their influence was mostly confined to New England and the most fertile collecting ground for old ballads was in Appalachia and other parts of the southern U.S. (maybe it was a Baptist/Pentecostal influence but I doubt that). Besides the Puritans were plenty superstitious. They burned witches didn't they?