In his late twenties, Colson Whitehead had a fugitive slave advert pinned over his desk: "Run away from this subscriber for the second time are TWO NEGROES ??? Both speak tolerable plain English and may insist on being called Cuffee and Khasa respectively. Whoever shall deliver the said goods to the gaoler in Baton Rouge, or to the Sugar House in the parish, shall receive all reasonable charges plus a genteel reward besides what the law allows."
The text, a shade too lyrical to be historically accurate, was written by Whitehead's Harvard University friend Kevin Young: the opening poem in his debut collection, Most Way Home. When it was published in 1995, Whitehead was writing cultural criticism for The Village Voice and working on a "terrible" novel with a "Michael Jackson-Gary Coleman-type" child-genius protagonist. He certainly wasn't brave or foolish enough to write about slavery.
His first successful novel, The Intuitonist, told the story of an African-American elevator inspector scapegoated by her white colleagues. His second, John Henry Days, interrogated the legend of a steel-driving man Whitehead has called "the first black superhero I knew". The idea of a novel beginning in the antebellum south and following fugitive slaves passing through American history along a literal underground railroad occurred to him between the two books. He didn't feel ready to write it.
When he wrote about racism, he did so with irony, always keeping his distance. He co-created a satirical pop-culture website, Nat Turner Overdrive, named after the leader of a slave rebellion. In The New York Times, he mockingly suggested the Southern Novel of Black Misery as a promising genre for writers short of inspiration. At talks and signings, he derided slave narratives as a played-out trope, knowing there was a scrap of paper in his drawer that would expose him as a hypocrite.
The Underground Railroad was a network of safe houses and routes north run by abolitionists and free black people. The metaphor originated in coded messages referring to "conductors" and picked up steam in the work of historians afflicted with white saviour syndrome. Although tens of thousands of slaves did find their way to freedom, on the eve of the Civil War almost 4 million men, women and children were held in bondage.
In the 1930s, the Works Progress Administration employed writers to interview former slaves. Reading one woman's description of the wooden shoes she was provided with, Whitehead imagined the carpenter that made them and was struck by "how vast the machinery of slavery was".
"If you're descended from whites who were here 200 years ago, you'd like to think that you would have helped on the Underground Railroad or been an abolitionist, when of course ??? you're a product of your time," he says. "How can I imagine what my family went through? Would they have been able to run or resist in their own little way?" He can trace his mother's line to 18th-century Virginia, his father's only to early 20th-century Florida. Details are scarce.
The Underground Railroad's opening section is set in Georgia, on a plantation owned by two brothers, one merely cruel, the other actively sadistic. Slaves are branded, whipped, beaten, groped and humiliated. One man's ears are bored for stealing honey, another's eyes put out for looking at words.
Twelve Years A Slave and Django Unchained reckoned with slavery by putting its horrors on screen in pornographic detail. Whitehead doesn't spare his readers, but says he was scrupulous about historical accuracy. In a scene describing a captured fugitive castrated, flogged for the entertainment of dinner guests, doused with oil and "roasted", he indulged in artistic licence by stuffing the man's meat in his mouth and sewing it shut, but was otherwise true to the record.
He chose a teenage girl, Cora, as his protagonist, partly to break a run of three books about men, but also to account for the additional abuses suffered by women: the inevitability of rape, whether by a master, an overseer or fellow slaves, and the obligation to bear children that could be sold at any time.
From the moment Cora and her fellow runaway, Caesar, descend to a railway station beneath a Georgia barn, Whitehead's commitment is to "the truth of things, not the facts". He originally envisioned them travelling through time, but after re-reading Gabriel Garcia Marquez, decided that "deadpan delivery of the fantastic would serve the story more than a straight science-fiction treatment".
So while the story of slaves on the run from a relentless tracker unfolds in a 19th-century setting, there are anachronistic touches in each state they pass through, representing the many ways white supremacy continued (and continues) to be expressed after emancipation, including eugenics programs, lynching as entertainment, Jim Crow race laws and the violent backlash to black progress exemplified by the destruction of a prospering African-American community in Greenwood, Oklahoma.
"Racial violence only becomes more vicious in its expression," concludes John Valentine, a mixed-race farmer building a utopian socialist haven for free black people in Indiana. "It will not abate or disappear, not anytime soon, and not in the south."
Because Whitehead wrote the book in 2015, as a new civil-rights movement was coalescing around the rallying cry Black Lives Matter, people often asked if it was somehow inspired by the police shootings of unarmed black men. "The answer was no." Because it hit the best-seller list last August, in the final months of the presidential election campaign, people asked if it was a response to Donald Trump's white nationalist rhetoric, and the answer was no to that, too.
Is it just a coincidence, then, that he was working on it at the same time as Beyonc?? was writing Lemonade, Kendrick Lamar was making To Pimp A Butterfly, Ta-Nehisi Coates was finishing Between The World And Me and Ava Du Vernay was shooting 13th? Whitehead frames this as a matter of black artists being afforded a platform rather than a collective cry of anger and frustration at the persistence of institutional racism under the USA's first black president.
"We have a new generation of African-American artists who have access to get their stories told, and I think if you keep making films and TV shows eventually you'll attack American history ??? I think it's natural that we have these moments of convergence," he says. Barry Jenkins, fresh from winning a Best Picture Oscar with Moonlight, a story of gay black love, has signed on to adapt The Underground Railroad for television.
Whitehead is continually asked to be "a spokesman for every segment of black life": to give talks about race, advise teachers what to do when a white pupil touches an African-American student's hair, to march and sign petitions and join demonstrations on the steps of New York Public Library. He generally declines.
"I'm pulling back, because I'm trying to get back to work. As a writer, I like to write, and that's how I've resolved to address what's going on. If you write about race in 1850 or 1960, you're also writing about race in 2017," he says.
"Last year I thought I would write a crime novel - sort of a different muscle to exercise - and then after the election of Donald Trump I thought 'maybe I'll pick up that other idea that's not as fun, and darker, and attacks racism in a different way than The Underground Railroad'." The new novel is set in Florida in the 1960s. He won't reveal more than that.
His impulse is to switch direction with each book, to expand his register and seek out new voices. Having found an audience with Sag Harbor, his autobiographical novel about summering in an African-American community on the Long Island shore, he "threw it all away by writing about zombies the next time", in Zone One. "I'm used to people being disappointed by my follow-ups," he says.
The stakes are higher now. In material terms, Oprah's endorsement changed his life more than winning the Pulitzer Prize - almost a million copies of The Underground Railroad have been sold in the US alone - but the critical consensus that he has written an important novel creates the expectation that he will write another.
"The last 30 pages I'm incredibly proud of. I've gone back to that final section a lot and I still feel that rush of creativity and the joy of doing what you set out to do. On the other hand, I'm writing a new book, and I have 20 pages and it's incredibly difficult," he says. "The Pulitzer is a great honour, and it's hard to see this constellation of good news happening again. I can take pride in the accomplishment, and then you start over."