I always thought that the majority of the USA had British ancestry, especially the states in the north and east. Now it turns out that most of the whole country has German ancestry. Even Florida and Alaska are mostly inhabitated by people of German descent.
Though there seems to be some logical mistake. People can't be of European
and "American" descent at the same time, except for the natives of course, but they already have their own place on this map.
Weirdly enough, there are no Swedes on the map. More than 10 million Swedes have moved to the USA. That's more than the whole population of Sweden today. Either they're confused with Norwegians or don't look at themselves as Swedes anymore.