There are 3000+ counties and county equivalents in the US, so that makes about 50 tweets per county. That could easily be output by one or two people per county

There are 3000+ counties and county equivalents in the US, so that makes about 50 tweets per county. That could easily be output by one or two people per county. Seeing as a lot of southern cities seem clean but with one or two really bright points nearby, I suspect that your thesis is correct and that most of these points are caused by particularly vociferous individual racists.