What is the historical context in Octavia Butler's novel Kindred?

s 1979
novel takes place in two periods of time, 1976, when the , Dana, has just
turned 26 years-old, and 1819, decades before the Civil War would finally put an end to
slavery.  Dana resides in Altadena, California, which is in Los Angeles County.  On that day in
1976, she is for the first time mysteriously transported back in time to a plantation on the
Eastern Shore of Maryland where slavery was very much a part of the local industry.  As Dana
notes with respect to the peculiarity of her situation,

Time travel was sciencein nineteen seventy-six. In eighteen nineteen - Rufus was
right - it was sheer insanity.

The Rufus to whom Dana
refers is Rufus Weylin, the son of a slave owner, and a troubled boy whose survival, Dana
discovers, is essential to her eventual birth.  Not unlike the film Back to the Future, but of
considerably greater moral weight, Dana discovers that she must ensure not only Rufus survival,
but that of Alice, the daughter of a free black who becomes enslaved as a consequence of helping
another slave escape the plantation.  Alice is impregnated by Rufus, beginning a lineage that
eventually produces Dana.