Colson Whitehead never writes the same book twice. This is possibly why, despite the fact that he’s been the most consistently excellent novelist to be published by a mainstream New York house over the last two decades, he hasn’t been able to build the audience that he deserves. In these times of fractured fandoms and increasingly algorithm-centric recommendations, people who enjoy Whitehead’s personal, semiautobiographical novel might not even bother to try his zombie novel, and fans of his zombie novel might not think his gigantic examination of the American myth of John Henry is for them. We expect the same things out of our novelists over and over again, and Whitehead has never been able to deliver that kind of dumb repetitive pleasure.

But there is a theme running through all of Whitehead’s novels, and his latest, The Underground Railroad, finally makes it plain. Whitehead is a writer who is interested in alternate realities. Not in a simplistic, Harry Turtledove-style way: he’s not writing dunderheaded books about what might have happened if the Nazis had won World War II. What I mean is that his novels always create at least two differing perspectives, and then examines the difference between them.

The Intuitionist, his debut, set the stage for the rest of his career by centering around a battle between two dueling philosophies of elevator inspectors: the intuitionists rely on feeling and emotion to determine the safety of an elevator, while the empiricists use tools and data. They employ two completely different methods to examine the same reality, and of course — humans being humans — the empiricists loathe the intuitionists. It is not enough in this world to be right, Whitehead seems to be saying, we’re not happy until the other person is actively proven wrong.

Of course, no two people look at reality in the same way. One of the best tricks of fiction is that it makes you believe you’re sharing a brain with another human being for a few hours. But the truth is that no reading experience is exactly like any other — hell, if you read a novel and then read it again after a couple years, you don’t read that novel the same way that you once did. If we can’t even share a reality with our past or future selves, how can we be expected to share it with other people who have completely different sets of experiences?

The truth is, we can’t. And that wouldn’t be too big of a deal if we weren’t always so damn concerned with controlling the experiences of other people — not just with making sure that they see the same world that we see, but that they feel the same feelings we do on seeing that world. Think of a toddler, always asking her father to look at the rocks or leaves or toys that she’s looking at. Think of a teenager who gets upset when he plays his favorite song for someone and they don’t immediately fall in love with it the way he did. Think of the evangelical who believes that everyone must be “saved,” which means that everyone must experience a relationship with Jesus in the same way that she does.

Whitehead’s work is about that distance, and the way different people react to that distance. John Henry Days managed to cram the biggest number of alternate realities into its pages in the form of the many different John Henry stories America has told itself over the years, from the sanitized cartoon film strip to the nastiest beerhall ballad. By panning out into a wide-angle shot, he constructed a mosaic portrait of John Henry from the shards of individual stories, an inclusive reality that took all the different stories into account as one mega-narrative. In Apex Hides the Hurt, his funniest and least understood novel, Whitehead addressed the way we create these alternate realities. The book is about a nomenclature specialist — a corporate naming consultant — who is called in to rename a troubled American city. Some want a name that honors the town’s racist past. Others want a glossy, shiny name that shellacs over past and current troubles. The only thing everyone agrees on is the fact that names are destiny. Names create a reality while also destroying other realities.

The semiautobiographical Sag Harbor is about a young black kid who spends the summer in a wealthy white vacation community. The alternate reality in Sag Harbor is created by privilege: rich people flee the diversity of New York City to relax among their own kind, in a neighborhood bolstered and protected by wealth. The protagonist kind of fits in, but he also doesn’t. Because he looks different, he represents a parallel world to these rich kids and their families. He’s vibrating at a different frequency than everybody else in town, and that makes some people highly uncomfortable.

Zone One was perhaps the clearest articulation of the distance that Whitehead is always navigating: in the New York of Zone One, the world of the living and the world of the dead exist in the same space. Zombies roam the city as humans try to retake neighborhoods and restart their civilization. The protagonist this time calls himself Mark Spitz — another naming trick, echoing Apex — and he shares some spirit with the main character of Sag Harbor: he’s living in a world that sees him as something to be chewed up.

Everything you’ve heard about Whitehead’s latest novel, The Underground Railroad, is true: it is a masterpiece, and it is his best book, and it might be the best American novel of the year. It tells the story of Cora, a young slave in the middle of the 1800s who flees northward on the Underground Railroad — in this reality, a physical railroad that swirls around under the surface of America — and occasionally coming to the surface to find different horrors along the way.

While the road trip novel may not have originated in America — the Odyssey had us beat by a few thousand years — America, with its wide-open spaces, certainly perfected it. Mark Twain got it right in The Adventures of Huckleberry Finn, but writers have been messing with the formula ever since, from On the Road to The Road.

The Underground Railroad is in that tradition: it travels across this country with an eye to understanding it. Like Huckleberry Finn, The Underground Railroad is profoundly interested in the American original sin of slavery. Like the characters in The Road, Cora travels from tragedy to atrocity and back again, though unlike Cormac McCarthy’s post-apocalyptic tale, the bleakness in The Underground Railroad serves a purpose beyond beautiful nihilism.

Whitehead treats every state in The Underground Railroad as its own independent universe, like the various stops in Gulliver’s Travels or the planets in Star Trek. The way each state deals with race is different — in some, the racism is made overt in a grotesque pageant, while in others the grotesqueries are kept hidden beneath a more sophisticated surface. But it is always there, and Cora always finds it before moving on to another destination. (In this way, The Underground Railroad shares a lot with Matt Ruff’s wonderful Lovecraft Country, which is itself a road trip novel through the heart of 20th century American racism.)

What is it about America that makes it so perfect for this kind of episodic travel narrative? Well, geography is obviously a huge factor. The United States is huge, and there’s just enough difference between neighboring states to keep things culturally interesting. But this kind of story works for America, too, because it’s the story of an individual. America has never been big on the idea of communities improving through collective action: the personal epiphany has always been our preferred method of change. Cora can change, and Huck can change, but the people they encounter along the way don’t have to change. The author can represent the horrors of racism and the deep, nearly mortal wound that is slavery without plastering on some phony resolution where everything is fixed. The readers can gape at it, we can make some necessary personal adjustments, and then we can move on.

Is there any hope for a world (or a nation) in which we all occupy our own alternate universes? If the distance between two people is an entire reality, what’s the point in even trying to communicate, on a planet loaded down with more than 7 billion different realities? Whitehead used to be content to just allow that question to sit at the end of his books, staring at the reader after the last page. That’s a big reason why Apex, for example, never found a larger audience: because Whitehead felt as trapped in his own reality as any of his characters.

Gradually, though, Whitehead has developed more of a heart as a novelist. You’ll find no easy answers in The Underground Railroad; one novel isn’t going to cure America’s broken heart. But the novel does offer a kind of answer in the relationship between Cora and her mother, Mabel. Years before Cora ran away, Mabel set out on her own. She disappeared, never to return. Even a maniacal slave hunter named Ridgeway could never track her down.

Cora, of course, is heartbroken that her mother would leave without her, and that she’d never returned to save her daughter from chains. The mystery of Mabel, that confusing stew of heartbreak and confusion and a demand for answers, is what drives Cora to run away, to ride the Underground Railroad on her own. She may never understand what happened to her mother, she may never walk her mother’s path, but she wants to know her mother’s truth, and the pursuit of that truth is difficult and long. It leads to places that Cora doesn’t want to go, and it shows her things she’ll never forget.

But that quest for understanding, Cora’s attempts to bridge the gap between her reality and her mother’s reality, is what makes the difference in her own life. The very act of trying to understand what someone else’s reality is like changes your own reality for the better. Walking toward the promised land changes you into someone worthy of the promised land. Even if you never get there, you will find yourself changed.

(Colson Whitehead reads at the Seattle Public Library this Saturday at 7 p.m. The reading is free.)