Wilco: It sounds as if you are looking specifically for songs that were written and were popular at (or immediately after) the time that these historical events occurred; is that correct?

The reason I ask is that there is a beautifully haunting song called "Kilkelly". It was copyrighted in 1983, but its lyrics are comprised of excerpts from letters written to the songwriter's great-great-grandfather in the US by his father in Ireland from the 1860s to the 1890s. It's a very personal glimpse into the pain of the families separated by that "mass exodus to the US" of which you speak, so even though it's not a song that has the "great historical significance" that a song of that period would have, I think it's still worth considering for your program.

Here's a link to the song "Kilkelly" (in Mudcat's "Digital Tradition" files): /@displaysong.cfm?SongID=3394