Well most of the mid-century immigrants were overwhelming catholic, yet, that didn't matter much, as signs like "No blacks, no dogs, no Irish" didn't have a religious requirement. And, in the 'melting pot' there was a lot less of the catholic vs. protestant in America and far more of an association with a 'mythical' Ireland. It's like a lot of areas have an Indian/Pakistani section/area. Where in the old country they were bitter enemies, over here (where we can't tell the difference anyway, and really don't care to) they have far more in common than what separated them in the past.
