A skillful writer of fiction can in a few strokes paint a city, culture and climate; often this involves poking a few places in the reader's brain and having the reader fill in the rest, often without realizing they are completing the puzzle with their own impressions. If anyone can beat Italo Calvino at this game, please recommend their work to me. In some ways Calvino's masterpiece If On a Winter's Night a Traveler is a set of one-chapter exercises in this endeavor, and it's no less enjoyable for it.
One of the interesting things about Calvino is he sometimes creates places, whole countries and languages, that aren't even real, and yet because they bear structural similarities to the constellations of characteristics of other places that are real, they seem recognizable. (Witness the gray, windblown, somewhat pointless seashore of the generic northern European country in Winter's Night. Hey, that was just like Poland's Baltic Coast! you might say. No way, it's those barrier islands in the Netherlands. No, it's Denmark!)
Speculative fiction grants many degrees of freedom so it might be interesting to use the exact converse approach - take a real place, but make one major change - government, demography, climate, culture. Imagine urban Iowa, the entire state choked by the smokestacks and shadows of a corroded, sprawling industrial mega-city. St. Louis and the Arch, shivering in the thin dry air of the North American altiplano, ringed by stony Mars-like valley walls shining with year-round snow. Detroit as America's Monaco-on-the-Lake, the decadent playground of heads-of-state and international CEOs. A Memphis apartment dweller goes to her roof in the middle of May to watch the ice break on the Mississippi, and a pod of killer whales soon emerges, chasing a harbor seal. "Okay, I get it", you say. Indulge one last entry: the ever-popular Empire State Building, all but its upper floors concealed beneath the shifting sands of a desert. Any worse than the Statue of Liberty sticking out of a deserted beach?
There are other games you can play in the counterfactual sandbox, alternative history among the most prominent, because that's how you can most credibly play with demographics. Maybe after the killer whales, the people of Memphis watch the Imperial Japanese Navy's icebreakers pass on the way to the international border at Kentucky. Maybe Missouri altiplano air is so thin that the criers of the Sunni mosques have resorted to bells which peal eerily in the wan mountain sun. But unless there are long stretches of time involved, it's hard to imagine, without relying on magic, how the ice could come in the first place. With the Statue of Liberty on the beach, we have some idea, and that's why typically this exercise is done in post-apocalpytic fiction where the world has tilted until it's barely recognizable, owing to some morally-deplorable actions of mankind. But it occurs to me that for these purposes deserts are somewhat oversubscribed. Why that might be is anyone's guess, so here's my guess. A literature unbound from the geography of the real world could, like a textual Rorschach (fancy!), betray the fascinations of its writers' culture. Why should deserts be so interesting to us? Open spaces, psychogenic self-discoveries, alien abductions and ancient civilizations are themes that all seem more at home out in the dust of South Utah more than the Illinois prairie or the warm salty nights of the Outer Banks.
It's interesting to ask to what degree the non-obviously-adaptive features of a culture or its government are uniquely suited to its physical environment, and whether individuals could tell if there were a "mismatch". Then again, maybe it's just familiarity or historical accident. It's easy to see why post-Crusades Europeans would be intrigued by the stories of potentates and harems at palm-fringed oases, or why the classic Greeks might have had such a crush on the Egyptians. But these are cultural, not climactic fascinations, and modern Americans know unfortunately little about the desert cultures that preceded them in the American Southwest. North America at least for the moment is populated by people who, relatively recently, emigrated from a continent that lacks deserts entirely. Even the desert Sunbelt is largely populated by internal emigrants from the wet and temperate East Coast. It's therefore tempting to speculate that once these people got to the deserts, they sensed that these rocky, open places somehow didn't quite square with the adaptive functions of the culture they brought with them. (Not that you would notice this looking at the green lawns in Southern California. Say it with me: "xeriscaping".)
Why this odd insistence on playing with counterfactuals? I think it's a way for certain individuals who love a place and want to internalize it to turn it over like a Rubik's cube, in the subconscious hope that this will somehow enable them to experience and understand it more fully, much like talking about a subject you're studying consolidates your grasp of the material. Michael Swanwick is clearly in love with his hometown of Philadelphia, although in The Drift he shows it to us after a much-more-severe Three Mile Island.
I'd love to see more vignettes of London overgrown with vines and jungle rot and crocodiles cruising the Thames or the people of Buenos Aires huddling with hot rum against another season of long Arctic nights, but maybe first I'll have to show you a new version of San Francisco. I'm not sure how I would abuse the City by the Bay with a pen, but I can promise that I will not feature sun-baked Alcatraz straddling on great dark rock, jutting above an expanse of cactus-studded sand.