That's interesting. I'm a brown upper middle class male and i've never felt uncomfortable anywhere in the country. That includes rural parts of Illinois, Georgia, and Virginia. Americans are really warm and welcoming if you approach them on their own terms.
The majority of Americans are decent people but at least 10%-20% of them are inveterate racists who are only nice to your face. When these white folks are among "their own" the bigotry comes pouring out of their mouths.
Who do you think nominated Trump? We should all be concerned that such a big slice of America sees nothing wrong with promoting a pugnacious narcissist fueled by a message of hatred. Just look at the healthy segment of evangelicals excusing his behavior even though the man hasn't a Christian bone in his body. All because Trump furthers their bigoted agenda.
It's entirely possible southerners are just nice to my face. But I don't think coastal folks are any nicer. I grew up in the latte liberal suburbs of DC, and man talk about people who can sit around spewing hate about people different from themselves.