Wonkblog maps the 173 pro-Confederate Flag rallies that have been held since the June 17, 2015 shooting of nine parishioners by a white supremacist (who has confessed to the crime and its motive) at a historic black church in Charleston, South Carolina prompted governments and businesses to disavow the Confederate Flag as a symbol.
The data was gathered by the Southern Poverty Law Center, which estimates a total attendance of 23,000 people, about half of which was at three big rallies: one in mid-July in Oscala, Florida to support a county decision to return a Confederate flag to government property with about 5,000 attending, one in North Carolina that drew about 4,000 people, and a KKK rally in Charleston, South Carolina in July, 2015 that had 2,000 supporters.
This isn't a huge attendance for supporters of what was reinvented as a symbol of opposition to the Civil Rights movement at that time, after having been mostly dormant for about seventy years, and has remained a potent symbol for white racists in the South (unfortunately, a group that includes most Southern whites) for about half a century. Keep in mind that referendums in more than one state have shown majority support among voters for the Confederate flag as a government endorsed symbol in Southern states in the last decade.
The many small rallies with just twenty or so supporters each almost make more of a statement by being pathetic and lonely than they do by showing mass opposition to removing the Confederate flag from government buildings. Also notably, many of the rallies had numerous armed attendees. And, ironically, a KKK rally isn't necessarily all that threatening, even if it is fairly big, because the KKK is right up their in popularity in American public opinion with Satanism and Nazis, even among large numbers of Southerners and is dead as a brand in places like Colorado where it once boasted that it had elected a Governor and a Mayor of Denver. The other two big rallies were a much greater cause for concern.
Mostly, the distribution of the rallies are what you would expect. But, there were a few surprises. I was surprised to see many more rallies in Ohio than in Indiana which has historically been more conservative and more politically aligned with the South. I was surprised to see no rallies in Coeur D'Alene, Idaho, a historical center of the white supremacy movement, while seeing them in Oregon and New Mexico which are not known for those leanings. There were fewer rallies in Texas than I would have expected, perhaps because the Texas flag provides an alternative sense of identity for Texans.