After William Faulkner bought his home on the outskirts of Oxford, Mississippi, in 1930, he made some alterations. He whitewashed walls, installed bookshelves, converted an outbuilding into a smokehouse and planted an English knot garden. Dissatisfied with the porch – which, initially, was barely wider than the front door – he extended the platform on either side of the central pillars. In black-and-white photographs of Rowan Oak, as Faulkner renamed the property, he sucks on his pipe and the porch is scattered with rocking chairs.

Standing in the cedar-lined walkway in front of it, the trees raggedy from ice storms and lightning strikes, Bill Griffith, the curator, observed that the extension transformed Rowan Oak into “a grand place”, more manor house than farmhouse; he likened the change to Faulkner’s anglicisation of his surname with that middle “u”. Through their musical variations on the themes of light and space, Faulkner realised, porches defined the character and status of houses in the American South.

I understand how he felt. When my family moved to Atlanta two years ago, our search for somewhere to live was directed partly by humdrum considerations of schools, cost and facilities. But, in one of those mysterious attunements that can develop between spouses – retrospective evidence of compatibility or maybe the osmotic consequence of living together – my wife and I shared another, more important criterion. The fantasy of our future in the South, our dream of trusting neighbourliness and the unhurried ease missing from our crowded life in London, depended and resided on an imaginary porch. The hammocks, balustrades and filigreed railings: they had bewitched us on a road-trip many years before and we wanted our own version. We had to have a porch.

Like many of America’s traditions, especially in the South, the porch is at once derivative and indigenous, a synthesis of multifarious influences into an American original. Some architectural historians think the concept was imported with and by west-African slaves. But other iterations of the same idea – a shaded outdoor space beside a too-stuffy house – have also been implicated: Italian loggias, Greco-Roman porticos, English colonnades, early colonial architecture in the Caribbean. Spain and France contributed latticed ironwork and other refinements; later came Gothic arches and the turrets and gables of high Victoriana. In the mid-19th century they were incorporated by housebuilders across the country, but in the South they were older and ubiquitous.

They have never been quite as innocent as I wanted them to be. Hybrid in origin, in its history and associations the porch is paradoxical. To begin with, it is at once public and reclusive. Like a negligée, it seems alluringly to lay bare a home, a family, its secrets, but also withholds them, the life that is out of sight somehow more opaque by being half-revealed – especially when, as many of the best porches do, it wraps around a house’s façade to make a zone of shady, unseen repose. And, while the neighbours might be able to see what you are doing on the porch, and with whom, your parents inside cannot.

Unsurprisingly, this has always been a place for courtship and assignations, in life and in art. “Sittin’ on the front porch on a summer afternoon,” Dolly Parton sings in “My Tennessee Mountain Home”; “And when the folks ain’t lookin’, you might steal a kiss or two.” Many of the romantic crises in “Gone with the Wind” occur on the porch. We meet Scarlett O’Hara, with her 17-inch waist, being courted by twins on Tara’s. From it she fatefully watches Ashley Wilkes riding up to the plantation and falls in love with him. Rhett Butler first propositions her on a porch in Atlanta, just before Scarlett sees the city burn.

If you care to notice them, porches are a dominant setting in Southern literature, with all its violence, mourning and zealotry. The flashpoints they host, in fiction and reality, are not only erotic: they are where people encounter strangers, eschew relatives, meet the outside world and escape it. In “To Kill a Mockingbird”, they are the way-stations, targets and refuges of Scout’s adventures, as well as posts for her neighbours’ surveillance, their secular evening rite. The climactic scene, in which Atticus thanks Boo Radley for saving his children’s lives, takes place on the Finch porch. Scout escorts Boo home; he lets go of her hand on his porch; she never sees him again. “One time [Atticus] said you never really know a man until you stand in his shoes,” she concludes. “Just standing on the Radley porch was enough”. A milkshake shack has ousted the house in Monroeville, Alabama, in which Harper Lee grew up, but a few turreted porches, with pretty hanging baskets, remain near the courthouse she made famous.

This is the scene of endings as well as beginnings: where newlyweds are photographed and pallbearers shoulder their coffins. Its soundtrack is the dead thud of the renegade Yankee’s head on the porch-steps at Tara, as Scarlett drags away his corpse, as well as the tell-tale squeaky hinge of innumerable lovers’ swing-chairs. Think of Edward Hopper’s sexually charged but characteristically unhappy painting “Summer Evening”: out on the porch, a young man eyes a woman, but she looks tensely away. The fate of the nation, as well as of doomed relationships, has been sealed there. After Robert E. Lee surrendered to Ulysses S. Grant at Appomattox, one eye-witness records, Lee “passed out to the porch…the general stood on the lowest step and gazed sadly in the direction of the valley beyond where his army lay – now an army of prisoners.”

Still, after reclining and reflecting on porches across the South, it seems to me that the most important tension they embody is the one at the heart of the American republic. They are at once egalitarian and hierarchical, an amenity which, in its more extravagant forms, showcases the opulence of a few, but which is available to everyone, as all American rights and chances are meant to be.

The extravagances can be lovely. Consider the Garden District of New Orleans, probably the country’s porch capital (though the two-storey side-verandas of Charleston are a plausible rival). The celebrities who live in the streets south of St Charles Avenue are heirs to a lordly 19th-century merchant class that signalled its leisureliness, and its Southern manners, through its sumptuous, wrought-iron piazzas.

Like good manners in general, though, a porch is a way to maintain distance as well as to extend courtesy. It is a standing invitation, hospitality incarnate, but the welcome it evinces is sometimes formal, or, to put it another way, insincere. It is as much a buffer zone and fortification as an embrace: those pillars and railings are also battlements. You entertain people there, but also intercept them.

Black people, for example. In the segregated South, servants were often the only black folk to enter the houses of white families. Black labourers might approach the back door or, occasionally, the porch, where a generous lady might provide a glass of cool water while issuing instructions. They could go no farther.

The porch, like the South as a whole, is suffused with race. The Palladian porticos beloved of the revolutionary elite, such as the one installed by George Washington at Mount Vernon, alluded to the classical slaveholding civilisations that some Americans saw as a model for their own. The Confederacy’s wealth is long gone and many of the cotton aristocracy’s mansions are peeling or decrepit; but the Ozymandian porches – in their geometric sparsity, not so dilapidated as the buildings themselves – still advertise the criminally acquired capital and obtuse elegance. Sometimes they can seem less specimens of Southern charm than carcasses or cages.

For all that, the porch is a democracy, too. Anyone of any race or station can enjoy it, because its essential features are not “jigsaw work on the porch banisters”, or “a fringe of wooden scrollwork” (embellishments Rhett promises Scarlett) but the elements themselves.

Across the Black Belt of Alabama, amid the sort of spacious hardship that is peculiar to rural America, beautiful porches belie the poverty of run-down homes. In the emptying hills of Tennessee, rickety poles support slanted porch roofs. In such places the porch is often less an ornament than an extra room, comfortably furnished with discarded sofas and easy chairs.

The appeal is fundamentally the same in Appalachia as in the palaces of New Orleans, as are the pastimes, which are scripted yet spontaneous. From your safe promontory in the natural world, you observe the darting fireflies or the light reflecting on spiders’ webs. You watch the rain. You listen to the crickets and the frogs, smell the mimosas, hydrangeas and magnolias. You knit. You have a drink. Once you might also have relieved yourself – as when Scout notices “an arc of water descending from [a neighbour’s house] and splashing in the yellow circle of the street light”. In 1976, a New York Times reporter speculated that true freedom was lost in the South “about the time [a man] had lost the irretrievable right to take a leak off his own front porch.”

Black or white, rich or poor, you talk. “We got friends walkin’ up and down,” says one of the old-timers who converge on a stoop in the Georgia neighbourhood they grew up in. “We just sittin’ out here havin’ a beer.” You talk and you tell stories, the cheapest form of entertainment in a region both hard-up and prolific with drama. Porches, in fact, are the origins of many Southern stories as well as their setting. Charles Reagan Wilson, a historian at the University of Mississippi, recalls asking the novelist Eudora Welty why the South produced so many great writers. “Honey,” she said, “we didn’t have anything else to do but sit on the porch and talk, and some of us wrote it down.”

On a stifling night, if the wind gets up a little or the ceiling fan whirs, and you sit very still, you might just survive the heat. Everyone can appreciate these pleasures, and no one can take them away.

The madeleine memories of lots of Americans were made on their parents’ porches, the rhythm, temperature and scents eliding in a childhood haze. Often they come from a time before air conditioning, which instigated the porch’s post-war decline. Cars hurt, too: they meant more fumes and less foot traffic, so fewer passers-by and impromptu hellos. Television drew people inside, to follow distant, fictional narratives instead of the micro-theatre of the pavement. People began to prefer backyard decks to streetside exposure. They became too busy to loiter in the evening; the aspiration to unbounded leisure that the porch represents increasingly seemed too remote to pursue.

But the porch didn’t die and, in many new developments, it is being revived, as homeowners flee the forces that threatened it in the first place – all those inauthentic electronic connections and overburdened working lives. Take our house in Atlanta.

It is newly built – but it has a porch. It is not, objectively, the archetype of our imaginings. The floor is brick, like Faulkner’s extension, rather than the classic wooden boards. It has no hammock or swing-chair; it lacks the lived-on loucheness that only extended habitation can imbue. But we kitted it out with rocking chairs, a bench our son made at school and some potted flowers. We take the newspapers out there in the morning, before it gets too hot, and read books there in the evening, rocking companionably, waving at our neighbours or watching the children play on the lawn. In the right light, and when a breeze obliges, it is what we hoped for: our own sovereign claim on a half-true American dream.