I have written multiple times before how US history is taught in schools in a completely sanitized form that distorts and erases what truly happened. People are given a rose-tinted view of the past, especially when it comes to the brutality that was inflicted on black people during the time of slavery and all the way to the present. This is why there is such reluctance by some to accept that the confederacy was actually a very bad thing and should not be honored in any way. The same holds true for the treatment of Native Americans.
In another excellent program, John Oliver looks at all the problems with the way US history is taught and offers suggestions for how it should be taught,