There have been more immigrants to the USA from Germany than any another European country. I always thought it was the British Isles.
That may have something to do with the sheer number of immigrants to North America with German hometowns. The Penn Dutch were actually Deutsch, and a great many of the religious migrations (Amish, Hutterites, Church of the Brethren, etc; the Mennonites were Swiss and Dutch) were of congregations and whole sects. The Kulturkampf in the 1870s led to some whole villages bailing out and crossing the Atlantic. A goodly fraction of German ancestor DNA turns up some Ashkenazi roots, although when I had mine done, Ancestry wasn't mapping that.