I HAD NOT noticed this before, but novels about slavery tend to traffic a bit in fabulism and fantasy. The ghost in Morrison's Beloved, for instance. The time traveling and chronological slippages in Butler's Kindred and Reed's Flight to Canada. Charles Johnson's Oxherding Tale and Middle Passage do not deal in the supernatural, but they do draw on the kind of wild invention and gleeful disregard of plausibility that one finds in an older kind of pre-Flaubert novel, like Smollett or the picaresque. About the only example I can call to mind of genuine straight-up-and-down realism is Edward Jones's The Known World.
Jones can't be the only example, but still I wonder, why so frequent a resort to the imaginary? Tentative answer: a fiction writer immersing her- or himself in a reality so grim, dehumanizing, and hopeless as racialized, commodified slavery would naturally want to conjure up some magical escape. Something like this may happen in the death camp chapters of David Grossman's See Under: Love as well. Is Beloved about Sethe's wanting a magical escape from the reality of her past so badly that she actually conjures it up, then lets it almost swallow her?
Whitehead's Underground Railroad is a bit of a return to the fictional vein of The Intuitionist, but by so returning it also participates in the lineage outlined in the first paragraph. For the first several dozen pages, we seem to be in a normally realistic novel about slavery, but when Cora and Caesar escape and find their way to a station of the underground railroad, it's in a tunnel, and has tracks, and a steam locomotive...in other words, Whitehead has with no forewarning at all whisked us into an alternative-history historical novel (à la Roth's Plot Against America) by the simple device of making literal the metaphor of the "underground railroad"--the network of people who assisted escaping slaves. (In historical fact, apparently, hardly regular or reliable enough to deserve the metaphor.)
The rest of the novel tracks Cora's progress along the railroad through various states, which turn out to have a variety of institutions and attitudes around slavery, slaves, emancipated slaves, and African-Americans generally. None of the institutions or attitudes correspond precisely to anything in actual historical existence in the Carolinas or Tennessee circa 1850, but they do seem emblematic of post-emancipation history in the alteration of hope and dread, in the many shades of white obtuseness, in the ever-renewed striving after liberation and the ever-returning unkillable slavecatcher. The novel thus cunningly telescopes a lot of African-American history into a story lasting (maybe) a year or two in (maybe) the 1850s.
Thinking about The Plot Against America in our President-elect Trump moment makes me wish a certain someone had not retired. Roth, thou should'st be writing at this hour.