Why was America a broken promise in Kindred?

Octavia Butler's Kindred explores Dana's venturing back in time to the Antebellum South. Dana, a black woman, endures violence and sordid conditions throughout her numerous stays on the plantation where her slave ancestors live and work. One conclusion a reader could draw from the novel is that, despite Dana's success in the modern world, her ancestors, and black people at large, were abused and given the short end of the stick in American history. That Dana herself is unwillingly made to witness and experience such abuse represents a person reckoning with his/her past and family history—this is something everyone has to do an one time or another. But Butler expands this examination of personal history by dealing with the larger issue of slavery. Perhaps she intended us readers to call into question the ways in which we deal with the archive, or the history of slavery. Dana herself expresses shock at the difference between what she has read in history books and what she actually experiences. At the end of the novel, she is deeply bothered by the fact that she will never know what really happened to her ancestors after the fire on the Weylin property. And, in fact, most black people who try to uncover their family history experience roadblocks due to the incompleteness of the archive's narrative. Thus, Dana realizes that, black people in America continue to be mistreated in principle because history often does not acknowledge their ancestors' perspectives. In this way, America's promise of freedom is often a broken promise for black people.