I hate to point this out, but your personal experience is belied by the objective data available. I am NOT saying your story is untrue, or invalid. Just that the empirical data available tell a different story.
Statistically speaking, Catholics and Protestants in the US began intermarrying in small numbers as soon as Catholics arrived on US shores. When Catholics arrived here they were greeted with prejudice, bigotry, and conversely, with offers to throw down the walls of the Catholic ghetto and integrate with society. Many did just that.
I see. And this applied to Catholic New Orleans how? Your demographics work for the rest of the United States but they don’t work for Louisiana which was a French territory, then sold to Spain, then returned to France and then sold to the US. We were Catholic from the very beginning. Both France and Spain monitored Protestant immigration and had laws barring the establishment of Protestant churches.
When I make a personal observation regarding my family, rest assured that I have the historical background, the anthropological background, and the genealogical background to warrant such a clearly labled personal observation. What Catholic ghetto in New Orleans or anywhere in south Louisiana?
We Catholics were the majority. There was very little in the way of “Irish need not apply”. (That would only have come from the few Protestants that the US said must be admitted). The Irish were here already - from the beginning. Where else can you find a Spanish governor by the name of Don Alejandro O’Reilly? St. Patrick’s was the second parish founded in New Orleans years before Black '47.
There were no Italian or Sicilian ghettos here. Italians and Sicilians got farms and spread out precisely because
we Catholics were the majority. So when I remark that my grandfather married my divorced Protestant grandmother, you better believe it was a huge deal.
Empirical data applies to the predominately Anglo-Saxon United States of that time. The empirical data for Louisiana and Texas is going to look a whole lot different precisely because of large established Catholic populations.
I don’t want to derail the thread, but I stand by my personal observations knowing that my ancestors have lived here since 1768 and knowing that so many of my “protestant” ancestors from the Anglo-Saxon US converted to marry my Catholic ancestors from Louisiana. (My sister and I have done the genealogy). Catholic ghettos, indeed.