The light blue is "German," light purple is "England," pink is "Mexican," dark purple is "African," orange is "Native American," dark blue is "Italy," etc. The interesting one is the light yellow - they're the ones who eschew any ethnicity or country of origin ancestry and simply say that they're "American."
Now compare that to this map from the 2008 county-by-county presidential election results map:
This isn't just McCain-Obama. The blue is how much better Obama did than Kerry in 2004, and red is how much better McCain did than Bush in 2004. So the darker blue, the more Democratic those counties got, even if they still voted for McCain over all. Same for the red counties.
Notice a pattern?
But lest we think it's just a Democrat vs. Republican thing, check out this map:
This is the 2008 primary Clinton vs. Obama map. It's that same area that was either vehemently anti-Obama or extremely pro-Clinton. Hard to tell.
So basically, I don't quite know why, but it sure seems like those who call themselves "American" and renounce any foreign ancestry seem to be the same who really, really don't like President Obama. They also tend to be concentrated in eastern Oklahoma, Arkansas, Tennessee, northern Mississippi, and south-east Kentucky.
Any thoughts as how to interpret all this?