system
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human
[DC Comics] Do we know why Gotham City became a cesspool of crime to begin with?

To me, someone who does not read comic books, it seems really strange how this ONE city in America became a hotspot for such a stunning amount of "exceptional" criminals. We have The Joker, Scarecrow, Poison Ivy, Mr. Freeze, Bane and many others who all began their criminal careers in Gotham. Is there a reason for this? What makes Gotham unique in that sense? 

Also, how is crime in the rest of America? Do we know how the ridiculous amount of crime in Gotham affects your average citizen, both in Gotham and among the general American population?
gpt
Post-COIE the canon has been that the city is literally and figuratively cursed.

"Dark Knight, Dark City" explained that a 18th century group of demon worshippers (including Thomas Jefferson for some reason) summoned a Bat-demon named Barbatos and locked it in the center of Gotham for a few centuries (which Morrison would later sort of reference in his Batman run).

"Arkham Asylum: Hell on Earth" had some other dude using the inmates of Arkham Asylum as blood sacrifices during the turn of the 20th century, which opened up a portal to hell under the building that called on people in Gotham to become psychotic and draw them closer to the Asylum.

In Dennis O'Neil's short story "Cityscape", he goes back even further and says Gotham was built around a makeshift asylum co-founded by a serial killer who wanted a home in the New World for himself and equally insane brothers and sisters (the story also invoked the real life legend of the "Wise Men of Gotham" for the reason the city in the comics got it's name), and would give them a steady supply of people to prey on for generations.

Going off sort of tangentially, there was a literal 'there's something in the water' explanation offered in a Legends of the Dark Knight story called "The Wise Men of Gotham", the novel "Wayne of Gotham", and in the Arkham videogame series.

In the comic and novel examples, both stories suggested that Bruce's dad, Thomas, was indirectly responsible for releasing some faint psychoactive drugs into Gotham's water supply many years ago, which could be blamed for creating both Batman and his villains. In the "The Wise Men of Gotham", Bruce debunks it, but in "Wayne of Gotham" it's confirmed to be the case.

In the Arkham videogames, namely Arkham City, it's established that there's a Lazarus Pit deep in the heart of Gotham and it's been leaking traces of it's psychoactive liquids into the soil and water for longer than the city has been standing.