Your question concerning France & Germany probably refers to a source that was called "
Prussia " for many years. This area would have included border countries both in Germany & France that were on the
Rhine River. In France , it would be the Alsace/Lorraine etc.. area ...
It can be confusing but when you research the census' in the U., S. , search source countries as
Prussia, Germany, France, Deutschland or the regions (
Hesse etc...). You will find that they will change in different census' depending on which country now was in posession of that region.
Good luck.