Something seldom considered is that penny broadsides were sold on both sides of the Atlantic. Finding a song from Ireland or England in Canada or the States does not mean necessarily that the song was carried verbally by immigrants or sailors. It could have been learned from printed text, and adapted by the singer(s). A single copy could have gone through several hands until it was discarded.

The Bodley and other institutions have large collections, but these broadsides probably represent only a small fraction of the songs that were printed.