Thanks to Justice League has finally been clarified. During Superman's walk across America, the Dark Knight shined a light on why the DC Universe seems to be built off of fictional cities rather than real-world ones.
Fans all know that more often than not, the heroes of the DCU can be found in cities completely unique to the comic book world. Batman is the protector of the city of Gotham, just as Superman keeps a watchful eye on Metropolis. And beyond its more iconic locations, the DCU has other places like the Question's Hub City or the Atom's Ivy Town. Nearly every iconic hero has a city or town of their own that is completely made up. And while places like New York City and San Francisco do exist, DC's greatest heroes are found in communities native to the DC Universe.
As it turns out, Batman has a very good explanation for why that's the case. In Superman #703 by J. Michael Straczynski and Eddy Barrows, Clark is continuing his journey across the United States to reconnect with the people he feels he's lost touch with. However, this draws the attention of Dick Grayson’s Batman, who stops Superman on his journey to hash things out with his longtime friend. Batman and Superman begin a discussion where Dick expresses his concern that Clark isn't properly dealing with the recent destruction of New Krypton. Superman turns things around on the junior Batman and asks Dick when the last time he or Bruce has walked among the people and seen what they're going through. The fruitless conversation ends when Batman reminds Superman that being outside the boundaries of places like Metropolis and Gotham puts completely unprepared citizens in grave danger.
The DC Universe Needs Cities Like Gotham
DC Comics using fictional cities such as Gotham and Metropolis is a well-known staple of the publisher. In fact, it’s one of the biggest ways of distinguishing it from its biggest competitor, Marvel, which primarily uses real-world locations (most notably New York). But rarely do the heroes of the world address why so many of their adventures and escapades take place in places like Central or Keystone City. Batman's words to Superman seem to suggest that DC's cities act as containment grounds for the rest of the DCU.
Obviously there’s some crossover between the DCU and the ‘real-wold’, such as Wonder Woman’s visits to Washington, or Jace Fox’s Batman operation in New York City. But the lion's share of superhero activity happens in cities intrinsically tied to their heroes. This stands to reason as villains and their crimes usually tend to emerge in response to the debut of a superhero. While it could just be a coincidence that smaller towns and metro areas aren't privy to superheroics, Batman implies that the Justice League's fake cities exist to keep as many big battles and villains away from unprepared people as possible.
