There are 21 counties in America where a substantial number speak German at home, which I agree is more fascinating than the amazing number where that is true of Spanish.
The real story lies in where, and in what other languages are included. Predictably, in my neck of the woods, it is Portuguese. There is enough of this that you see a demand for portuguese speakers to work for doctors, and bilingual signs in places like banks. The same applies to Chinese in Eastern Massachusetts. When I lived in Quincy, you were almost out of place if you weren’t either Irish – and not necessarily umpteenth generation off the boat – or Chinese. Bilingual signs everywhere, and a Chinese supermarket near my apartment.
No surprise there’s a lot of French up near the border between Canada and the Northeast.
Surprising might be the lack of Pennsylvania counties where German is 10% or more, and the number where it is not the highest even when looking at the specs for the uncolored counties that fell under 10% of one or another.