An American driving into Mexico for the first time may reasonably feel excited. “I’m a gringo of good will in a small Buick! I’ll try to observe your customs!” he might say to himself, while waving at the locals. But seldom would he actually ask them a question such as, “How do you like living here in Mexico?”

Only the blithe presumption of an enthusiast like Ray Midge could be capable of such an overture. Midge, to whom the above quotes belong, is the hero of Charles Portis’s hilarious 1979 novel “The Dog of the South” (253 pages, $15.95), which has just been reissued by Overlook Press. Mr. Portis has a cult following, but he deserves real popularity.

A reclusive Arkansan clearly drawing on the same twisted Southern charm as the short-lived John Kennedy Toole, Mr. Portis recalls the overmothered-yetmotherless worldview of Walker Percy and, more distantly, the deadpan violence of Flannery O’Connor. When Midge says, “I didn’t know who Otho was but it was hard to believe that any person in Louisiana had ever keeled over from fraud shock,” we know we are reading a Southern writer. But when Midge announces, “I soon became fatigued from making so many judgments, half of them wrong, and so I gave up on making them,” we are truly in tune with the Southern psyche: unapologetic, sweetly pitiful, and just a little too eloquent.

At the same time, Mr. Portis can read like Don DeLillo by way of Stanley Elkin; he has a lot of postmodern detritus on his dashboard: “There were Heath Bar wrappers, at least forty of them, all over the floor and seats.” Driving down to Belize in pursuit of his wife, Midge encounters some men with very thick heads, all of them cobwebby with secret knowledge. The eponymous dog of the south, an aging con man called Dr. Symes, introduces Midge to the cult of John Selmer Dix, M.A., a self-help writer whose book “With Wings as Eagles” is the only one you need. Midge is skeptical, but too desperate to ignore it: “There might be some useful tips in those pages, some Dix thoughts that would throw a new light on things. I was still on the alert for chance messages.” Mr. Portis even has one novel, “Masters of Atlantis,” all about secret societies.

But he also has “True Grit” (Overlook, 224 pages, $14.95). There is usually a reason why an author has been overlooked, not always just, but explanatory all the same. In Mr. Portis’s case, it may simply be that he hasn’t taken himself seriously in the way Thomas Pynchon or William Gaddis has; it may also be that his work too quickly calls up the names of so many other writers. But it’s most likely that “True Grit” the novel (1968) was fatally overshadowed by “True Grit” the Oscar-winning John Wayne movie (1969), and that John Wayne’s portrayal has soured and sucked the color out of Charles Portis’s reputation.

The novel itself is a crisp adventure, almost a children’s story, but it has a narrative tack that only adults may fully appreciate. Mattie Ross, the 14-year-old girl who drags Rooster Cogburn out into Indian Territory to avenge her father, writes about the experience from old age, having acquired a spinster’s confident tongue. Her voice is at once young and old, as though Mattie’s personality were preternaturally consistent, tempered early by biblical training and harsh reality. She doesn’t even use contractions. “Some people will take it wrong and criticize me for not going to my father’s funeral. My answer is this: I had my father’s business to attend to.”

Nothing is finer in this book than Mattie’s occasional digressions on politics and Presbyterian schisms, or her tenacious arguments with stingy horsetraders and careless gunfighters. Mattie does not offer herself as humorous, as her onscreen counterpart does.

The point of the story is to contrast Mattie’s idealism with Rooster Cogburn’s rascality. Both are gritty, but in the book idealism wins the day, partly because it is so piquant on the page. This goes far beyond “pluck”; it is moral fiber, resonant and taut as Mattie’s clean sentences.

A simple comparison between Mattie and Midge says a lot about Mr. Portis’s depth. Both live in the grip of peculiar self-confidence. Midge is a nerd in a realistic way: His enthusiasm for meaningless things makes him superficial. Mattie, on the other hand, is bibletaught but ultimately her daddy’s girl in matters legal, commercial, and martial. Mr. Portis has much to teach us about the tension between shelter and range, the drama of the southern ego as it emerges, onto Oklahoma, Texas, and beyond.

blytal@nysun.com