Just saw a comment that made me wonder. All these separate lineages came under the banner of "White" and here we are today, and they all work to spite us.
Donald Trump is of German descent
Mitch McConnell is of Irish Descent
etc
The real answer is the period between 1924 and 1965. Americans of Western European (and Protestant) descent turned on non wasps, passed immigration act of 1924 to reduce amount of
non desirable immigrants. Said that the jews, italians,irish,etc weren't assimilating into mainstream American culture because of flood of people from their nationalities/cultures into the country.
Without new countrymen coming in, the assimilation process was sped up for the white ethnics that were here. They intermarried more and blended more into white mainstream society........switched religions, anglicized names,etc
When the Civil Right Bills passed, and discrimination was made illegal technically, they took advantage of new education and occupation opportunities previously blocked to them.....and fully integrated into mainstream white American culture.