Kindred by Octavia E Butler (first published by Doubleday, 1979)
Octavia E Butler was a writer of powerful, thought provoking science fiction who died much too soon. She was also African-American, and all the books of hers that I’ve read so far have black main characters.
This is a time travel story, told from the point of view of Dana, a black woman married to a white man in 1970s United States. She finds herself transported back in time again and again to Maryland in the time of slavery – always to save a life, and often stuck there for long periods. It becomes clear that these involuntary time trips are bound up with the history of her own family. Because Dana has to live on a plantation while she is in the past, she is able to observe what it is like to live under the system of slavery first hand, and how it warps the lives of everyone, black and white, that it touches.
Octavia Butler won awards for other novels, but not for this one. Maybe it cut too close to the bone, even though she said in interviews that she had somewhat sanitised the experience of slavery. However, it is her bestseller, and often used for teaching purposes in the US.