There were large swathes of Americans in those generations who stopped using German publicly because of World Wars One and Two. German was at the time the second most commonly spoken language at home in America. You still see vestiges of it in recorded data about ancestry [1].
I suspect many among them would've largely forgotten a functional knowledge of German by the ends of their lives, even though it was their mother tongue and kitchen table language growing up.
In the heart of Pennsylvania Dutch Country was a town that Bismark that changed its name to Quentin after Quentin Roosevelt died in the Great War (WW I).
I suspect many among them would've largely forgotten a functional knowledge of German by the ends of their lives, even though it was their mother tongue and kitchen table language growing up.
[1]: https://en.m.wikipedia.org/wiki/American_ancestry#/media/Fil...