Contrary to popular belief, there are more Protestants of Irish heritage in the US than there are Catholics of Irish heritage. Just under half of Irish-Americans identify as Protestant, while only about a third consider themselves Catholic. It's much closer if you ask whether they were raised Protestant or Catholic.
https://religionnews.com/2014/03/17/irish-americans-religion-politics/
Some of these are Mike Pence type converts from Catholicism to Evangelicalism but most are Scotch-Irish borderlanders.
