Apocalypse Not

An unfortunate side effect of combining After the End and Expansion Pack World.

This is the tendency for an initially hellish, ruined post-apocalyptic setting to become less and less so as the world is developed due to the addition of additional cultures with healthy and growing societies. Often also "helped along" when the knowledge that has been lost seems less and less significant with the development of new Applied Phlebotinum, often of a type not available before The End.

Compare There Is Another, when a character said to be the Last of His Kind turns out not to be as more and more about his kind is revealed.

Contrast with New Eden, where the healing of the world is central to the plot rather than an unintentional side effect of its development.

Anime

 * Mai-Otome. Apparently, despite the claim that the war 300 years ago left the world devastated, the desert extends to just the immediate surroundings of Windbloom, and everywhere else it is lush and beautiful.
 * Macross suffered from this, possibly because the post-apocalypse episodes were made in a hurry after the series was lengthened.
 * Don't they have cloning technology? Between that and the biomass contained in the relics of the destroyed Zentradi ships, they could have easily recreated their population from what had survived. And I recall the background materials openly stating that.

Film

 * The film Warrior of the Lost World was mocked on MST3K for how clean and nice the post-apocalyptic world looked.

Literature

 * The Mortal Engines novels suffered greatly from this, to the point that it seemed that the only thing that civilization had lost was the technology of the Wave Motion Gun and modern era CD-Roms.
 * Both played straight and subverted in Dune and its sequels: Paul Muad'Dib establishes an environmental program to turn the originally hellish-desert planet Arrakis into a more verdant and fertile place to live... only to have his son disrupt the process, showing how a verdant Arrakis would create its own hellish political climate... only to, during his own reign over the universe, turn it into a verdant world with only a thin strip left of the original desert... only to turn it back into its original desert harshness as part of his plan for the continued preservation of the universe. Honestly, Arrakis goes back and forth from temperate to desert climate so often that it's pretty much impossible to tell whether a given situation is upholding this trope or setting it on fire and tossing it out the window.
 * It's actually even more complicated; Arrakis was originally a pleasant planet before the water-hating "sandtrout" arrived.
 * The Deathlands action/adventure novels (by Jack Adrian et al),
 * A large part of the plot and theme of The Stand by Stephen King is whether or not this will happen to what remains of civilization after the superflu.

Live Action TV

 * Jericho's first season focused on a small town struggling to survive after nuclear attacks destroy major US cities. Although the town itself isn't ruined, they increasingly struggle against typical post-apocalyptic challenges: finding food and medical supplies, fending off raiders, generating power, relations with neighboring towns. In season two, many of these challenges go away, as the focus shifts to.

Tabletop Games

 * In Rifts, Earth has been ruined by the apocalyptic return of magic; yet the world seems stuffed to the rafters with powerful, advanced cultures wielding incredible technologies or magics. This has to do with the Rule of Cool, the Fantasy Kitchen Sink and the fact that All Myths Are True.
 * Technologically, perhaps, but with few exceptions, most places culturally are barely out of the "Me big man with gun! Me boss!" stage. And it only got more brutal as new splatbooks came out.

Video Games

 * Arguably happens in Fallout 2; at the beginning, humanity seems to have reverted to Stone Age tribalism, and it's not until the second town that you even find an actual gun available for sale. By the end, all the Mooks have Powered Armor and energy weapons out the ass.
 * Note that the fact that civilization has mostly rebuilt itself is pretty much explicitly stated more than once, and is actually a significant element of the setting. The quality of life in San Francisco and the New California Republic is shown to have nearly reached prewar standards, and even poor frontier towns like Modoc generally have some sort of government.
 * Made even more explicit in Fallout New Vegas. The only people having a difficult time making ends meet are the N.C.R., who are that way due to overextending themselves, the Followers, who are actually using the supplies to help other people, and the poor around Vegas, most of whom lost their money to drugs and gambling.
 * At the end of Deus Ex, JC Denton shuts down global communications, triggering the Great Collapse and throwing humanity into a Dark Age. Somehow, after only 20 years, civilization is back up to its previous level, and unfortunately the same Illuminati-controlled dystopia DX 1 started with.
 * 'Previous level'? Deus Ex was cyberpunk, Invisible War is full-blown sci-fi; civilization ADVANCED.
 * Definitely 'previous level. The upcoming game Deus Ex,Human Revolution, which takes place a few decades before the original Deus Ex, shows humanity in a golden age of technological growth and development. Apparently there was a massive economic collapse which lead to the stagnant world seen in the first game. So, when JC triggered the 'Great Collapse', he basiclly hit the reset button for the global economy and governments, which, in turn, allowed society and technology to start moving forward again.
 * Without explanation, the Crapsack World of Command and Conquer: Tiberian Sun has somewhat improved, in contradiction of what the backstory says, by the sequel Command and Conquer: Tiberium Wars.
 * Somewhat justified. Around the time in Tiberian Sun, GDI had little means of stopping Tiberium spread and not even the most advanced cities were protected from Tiberium spread or Ion Storms. In addition, GDI had not yet assumed the role of government, leaving most civilian services crumbling and national governments barely keeping control. When the situation got too bad, GDI would simply mass-evacuate citizens to its un-touched arctic colonies. The change we see in Tiberium Wars is the combined result of discovery of sonic weapons' effectiveness against Tiberium, the decision to wall cities up (blue zones) and GDI assuming the role of government, not to mention the aid of the Tacitus' secrets after Firestorm.
 * Arguably, Advance Wars: Days of Ruin/Dark Conflict goes like this halfway through. The beginning of the game implies worldwide destruction, with few survivors and no hope. However, we later see functioning cities, functional industry and many soldiers on our way, implying there isn't such a shortage of people after all. It's mostly Gameplay and Story Segregation though, since the cutscenes still give the apocalyptic feel.

Webcomics

 * Arguably part of the background for Terinu, as five hundred years previous to the story's start the Varn Dominion destroyed human civilization and scattered them to re-education camps among the stars. Things Got Better and humanity eventually took the Earth back, after the Varn were nice enough re-terraform it and remove all the nasty pollution.

Real Life

 * The Black Plague, credited by some historians with starting the ball rolling for Western civilization
 * Then again, other historians claim it actually set civilization back a few centuries...
 * Bikini Atoll represents this trope on a small environmental scale. Today, mere decades after several apocalypse-level nuclear tests, it is a thriving wildlife habitat.
 * It's still dangerous to land mammals, however, since the edible plants have absorbed radioactive minerals.
 * The Chernobyl exclusion zone is by no means a safe area even decades from the disaster, but the destruction of everything living that many foresaw would happen through horrible mutations never took place. There have been mutations, and certainly many animals have died from the radiation in their food, but evolution has done its work, and through natural selection vegetation and wildlife in the area has grown more resilient to radiation damage, and has been reclaiming the area with fervor.
 * The fact humans tend to avoid Chernobyl exclusion zone has helped a lot.