Beneath the deadening lack of racial diversity in American publishing lies a subtler, affiliated kind of redlining. Whether it’s a barrier constructed of ignorance or cemented by anxiety, it serves to keep most novelists — particularly most white novelists — working within the realm of their own racial heritage, creating characters that look like they do.

Almost 150 years after Mark Twain sent Jim down the Mississippi River, we still can’t decide whether that portrayal was a breakthrough or another inscription of racism. But no matter how much the country has changed, there are few towns in the United States as monochromatic as the towns in American fiction. Even as we try to encourage more diverse books, our eagerness — and capacity — to rain down hellfire on authorial missteps and insensitivities, conscious or unconscious, has radically increased. At the National Book Festival last year, Gene Luen Yang, who was newly appointed the National Ambassador for Young People’s Literature, said, “I have noticed an undercurrent of fear in many of our discussions. We’re afraid of writing characters different from ourselves because we’re afraid of getting it wrong. We’re afraid of what the Internet might say.”

The exceptions last year were striking, sometimes daring. The leading character of Garth Risk Hallberg’s mammoth “City on Fire” is a gay black man, a rare double-twist for a straight white novelist. In Nell Zink’s subversive comedy “Mislaid,” the white heroine and her daughter pass as black, moving undetected through a swamp of racism and white guilt. But perhaps the most interesting recent example comes from T. Geronimo Johnson, an African American novelist who realized while writing “Welcome to Braggsville” that his black protagonist should be white. That switch leaves a residue of ambiguity in this wickedly funny and disturbing satire about America’s confused and confusing attitudes about race.

When I asked Johnson if he thought white authors were reluctant to create black characters, he quipped, “I wish more of them would be reluctant.” And there’s the rub: Crossing the color line and crossing it effectively are two distinct acts. Jabari Asim, editor of the NAACP’s magazine the Crisis, singles out a few white novelists such as Madison Smartt Bell, Susan Straight and Colum Mc­Cann. But in general, he says, “Many books have black characters in them, but few seem to include black people.”

Author Charlie Smith (Daniele Sero Smith)

Into this fraught discussion now comes Charlie Smith, a 67-year-old white Southerner, who has just published a gorgeous, harrowing novel called “Ginny Gall,” in which essentially all the characters are black. In fact, the few white characters who appear occupy the kind of peripheral, broadly drawn positions too often reserved for minorities.

His story covers a great swatch of the Jim Crow South and conjures up the largely separate, ferociously repressed world of African Americans in the early 20th century. The protagonist is Delvin, born in 1913, to a “good-time gal” in Chattanooga, Tenn. Early in the novel, his mother unintentionally kills a white man and runs for her life. Delvin is left first to the care of an orphanage and then to a kindly undertaker, from whom he learns the mechanics of death and the rhythms of grief. He’s a bright boy, “a wonderanemous child,” quick to read and eager to make up stories, but his primary occupation is staying alive in a society that insists black men — even boys — remain dumb, shiftless and unthreatening.

In her “Glossary of Harlem Slang” (1942), Zora Neale Hurston defined Ginny Gall as “a suburb of Hell,” and that’s frequently — but not always — the terrain of this novel. In opulent, slightly antique prose that suggests Smith’s parallel career as a poet, “Ginny Gall” portrays a region infected with the presumption of black depravity and violence. Delvin and his friends live with the visceral knowledge that any violation of the rules, even the shadow of an infraction, will inspire the full ferocity of white rage, “as if this furious clumping together, this scarifying, claiming vengeance or redemption, was as natural as sunlight.”

One of the many outrages that Smith portrays so powerfully is that white atrocities must never be acknowledged, the veneer of Southern gentility must never be scratched no matter how horrific the crime. That unspoken rule constantly threatens Delvin’s later employer, an itinerant curator of black photography. His collection is “built to blow the foolish, sanctimonious notions of these folks right out of the water,” but he and Delvin step lightly around the South. “The world belonged to the white man,” Smith writes. “Delvin and his kind were merely scumbling through it. They were stranded in a country whose language was not theirs and whose customs were foreign to them.” Fortunately, Delvin’s employer is a master at placating local town leaders with happy pictures of “antic burlesque,” while secretly displaying photographs of lynchings for their real patrons.

Negotiating this treacherous landscape, Delvin is an incredibly endearing, absolutely heartbreaking figure. Without sentimentality or condescension, Smith follows him across the South, through periods of peace and sparks of terror, months of romance and long, unending trials of despair.

Despite being the author of more than a dozen well-regarded novels and collections of poetry, Smith has maintained an unfortunate degree of invisibility, which I pray his latest book corrects. He effectively left the South when he was 14, but his quiet, pensive voice is still inflected with a Georgia accent. From his home in New York, he admits that he came to the subject of “Ginny Gall” without any special knowledge of the material.

“I tend to write about stories and about characters that are not really part of my own life or my own experience because it’s more exciting to imagine things than to try to just relate factual matters,” he says.

“In one sense, I think in the world we’re all frogs in the same bucket. Whatever is going on, whatever misalliances and misdelving of quiddities we get into, the human heart is still beating in the same way in everybody’s chest. We want to be loved, we want to express love, we want to have our feelings about ourselves and our lives treated in an honorable way. We’re all struggling along those lines. So to some degree, we’re all the same.”

He takes gentle exception to my suggestion that Delvin’s story offers a powerful social critique.

“I’m attempting in a novel not to take a stand about anything or represent anything or points of view — that way of life or this way of life,” he says. “I’m not any sort of polemicist or writer of that kind. But I was drawn to that sense of a life having to be lived in that way. I wanted to see, in a sense, how strong the heart could be. What I’m trying to do is get a character to be real, to be speaking from a body that has a heart in it, from a being that has blood rushing around its veins and has ideas and notions and thoughts and losses and joys. That seems to me to be my obligation and my task.”

He was inspired by the trials of the Scottsboro Boys, nine African Americans who were accused of raping two white women on a train in the early 1930s. Smith says that “calamitous experience” caught his imagination. And for him, a novel is “a pure act of imagination.” He admits, “There were a few matters that I felt I had to look up, things I just didn’t know anything about. Hobo train riding was one.” (The novel contains a freight of Depression-era slang.) But he makes no claims to historical fidelity. Nor does he feel as though he’s trespassing on anyone else’s material.

“As far as the matters of racial consciousness or whether or not this kind of person can write about that kind of person, that seems kind of dangerous to get into. To decide only certain persons can write about certain things, that’s a kind of moral censorship, the most dangerous censorship — by the will of the collective — a way of looking at things that limits rather than opens. To hold myself back and say, ‘I can’t write about these matters because I don’t have any experience of them’ is to admit that the imagination itself must be limited, must be curtailed.”

“Ginny Gall” is a dramatic demonstration of that ideal. The second half is largely the story of Delvin’s adventures in jails and prisons — that vast network of cages that conveniently replaced the system of human chattel that the Civil War dismantled. The slowly turning gears of Southern law mesh perfectly with the teeth of racism. But Delvin persists through beatings and betrayals and the ravages of malaria, always reaching toward a life he imagines might be possible.

“It wasn’t all grief,” Smith writes near the end of the novel, but not near the end of Delvin’s trials. “Mingled with the pasty, durable, extenuated sadness was a happiness, a new one, a stretching out of himself, long-shanked and agile — he was, in this moment of American time, free, a misplaced man, overlooked, drifting on the breeze, a wanderer amid the garrison of interlockedness, sunk deep enough in negro life for a while not to be missed, uncounted by any census, omitted by the tax man, skipped by the army.”

Here, in these remarkable pages, he’s not overlooked. He’s seen and understood in a way that each of us — across the whole color spectrum of humanity — deserves to be seen and understood.

Ron Charles is the editor of Book World. You can follow him on Twitter @RonCharles.

Ginny Gall

By Charlie Smith

Harper. 451 pp. $26.99