The upper middle classes emigrated to US. In more favorable cases even upper classes(successful revolutions in Europe).
E.g., the German 48'ers (and all those bourgeoise folks fleeing the Commies). As to the potato famine Irish, the controversial Banfield, in the
Unheavenly City, claimed that their blood lines largely died out (not much of a social safety net then, particularly for the loathed and the damned). The Irish we have today, asserted he, came starting in the 1850's (that decade that had the highest percentage of immigrant arrivals to total population of any decade in US history, including recent ones, and which tipped the balance of power against the South since nearly all of them settled north of the Mason Dixon Line (the South seceded too late as it were to get away with it).