I am not sure about the specific wording of laws in the US before the Civil War, but I do know that many of the Confederacy’s documents specifically used the term “negro slavery”. You cannot separate the race from their victimization. It is not racist to say that black people were slaves in America’s past. Even if there were a few exceptions, much of it was encoded into law.

On the other hand, like the tweets say, just because a person was white doesn’t mean they owned slaves, or that they weren’t abolitionists.