Most people in most places are basically friendly. However. Even just being recognize you as 'other' can get old, like being asked "where are you from" or riding the bus in Chicago and having to answer questions about my ethnicity from whoever was feeling tipsy enough to ask them.
Here's one story of folks being un-friendly: I was at a public event, basically a version of a county fair with my wife's family somewhere in the rural midwest. There's a stage with small-name bands performing, food vendors, and a small carnival-ride section. As the sun sets we lose track of her parents, and as we're looking for them I also got separated from my wife. I felt like the crowd was also slowly changing and like I was starting to attract attention in the form of unfriendly looks. I find my wife and try to express this, but her face clearly says it's all in my head and why am I talking about anything other than how we can find her parents. Just then a physically imposed man walks up, plants himself firmly in front of me, and asks in the least friendly way possible, "how's it going brother?" I answer him in unaccented neutral native-born american english (don't remember what i said, but likely something like "good how you doin"), and my wife is like, "ok you're right, we have to find my parents and leave."
So just to be clear - I can't know what might have been, but I strongly suspect that having grown up here and being a native speaker made that evening simpler. And again, I'm someone who many people look at and just process as "white" so I can easily take my experiences as a shallow sample from the tip of the iceberg.
And that kind of "unfriendly" experience is something that happens more often if i leave coastal metropolitan areas.