As someone who lived in South Dakota for a few years, I can say with fair certainty that it has nothing to do with their ethnicity. People in small towns do not like new people in their small towns. I know of someone who grew up in one of those small towns, moved to the city (30 mins away - his parents still live there), and is now treated as an outsider. If you live there, you have to always have lived their. If you leave, you don't exist anymore. Yes, there are reasons these small towns are small and getting smaller. They cannot cope with new people in their midst.