Before the famine the Irish, self described, were Scots Irish and Protestant. These Irish started heading West in the 18th century due to the Rack Rents and impositions by the Anglican Church on their faith. This accounts for the many of the Irish families in the south.
Then there were the very early Irish Catholic families in New England who became Protestant because belonging to a Church was required, mainly servants, so they converted.
There’s a character in A Tree Grows in Brooklyn who converts to “better” her children. My family never did but they did grow into the middle and upper middle class eventually.
Today, about a third of the Irish in America are Catholic.
“One of the problems that many have is the definition of Irish and the label of Catholic. Before the famine the Irish, self described, were Scots Irish and Protestant. “
That’s true to an extent, particularly concerning the use of the name Irish, but there were some Irish Catholics in the colonies. I have both Protestant Scots Irish ancestors and Catholic Irish ancestors who came to the colonies before the Revolution.
The Scots Irish had helped the English defeat the native Irish and had settled in Ulster. IIRC after being double crossed by the English many of them left Ulster for British North America. They were a mixture of Scots and northern English and were Presbyterian.
My Irish Catholic ancestors were gentry who owned estates somewhere near Cork but they had their property confiscated by Cromwell. I’m sure that the theft of their property prompted them to leave for America. This exodus wouldn’t be well remembered because it happened in the late 1600s and the numbers wouldn’t have been large. And at some point they might have become Protestants like my family line did.