If we avoid mass fatality in the Potato Famine, might the result end up being not less, but more Irish immigration to America? After all, the POD means there are more Irishmen, and thus even greater pressure on marginal farming land and so even greater emigration.
But assuming, for some reason, that we see less Irish immigration than OTL, might we see more Portuguese immigration than historical? While not nationally significant, there is a large community in New England, which is made up mostly of people who came through the Azores and Madeira, and now Cape Verde. Or, in the 19th century, is the pull of Brazil just too overwhelming for any would be Portuguese migrants?