The confederate flag was raised and put on government buildings between 1961 and 1962...when the Civil Rights Movement was moving into the area of making sure black people could vote.
Sounds like THAT FLAG was pressed into service so as to signify white supremacy on two independent occasions. No wonder
Black Lives Matter,
Southern Poverty Law Center,
and various White Power Groups
have never, ever been confused about what this flag means.
If there is something else that anti-racism and pro-racism groups agree on 100%, I don't know what it is.