How did Batman manage to fight crime for so long without getting lost? Although the Dark Knight has been the guardian of Gotham for 75 years, the city's streets weren't mapped until 1998.
Writing at Smithsonian magazine, Jimmy Stamp reminds us that Gotham didn't become the official hometown of Bruce Wayne until 1940, when Batman co-creator Bill Finger named the city for the first time in Batman No.4. Prior to that—despite its resemblance to New York—the city was purposefully generic, so that readers could identify with it, regardless of where they lived.
Gotham City's limits were defined in 1998 in preparation for the "No Man's Land Story" story arc, during which the city was cut off from the United States after nearly being destroyed by a cataclysmic earthquake. Enter artist and illustrator Eliot R. Brown, the cartographer of Gotham:
The first step for Brown was to meet with the writers and artists who shared their wish-lists for Gotham locales. As he recalls: "The DC Comics editors made it clear that Gotham City was an idealized version of Manhattan. Like most comic book constructs, it had to do a lot of things. It needed sophistication and a seamy side. A business district and fine residences. Entertainment, meat packing, garment district, docks and their dockside business. In short all of Manhattan and Brooklyn stuffed into a … well, a nice page layout."
With research materials in hand and a mandate that Gotham had to be an island, Brown began, like Bill Finger, with the idea of a fictionalized Manhattan. Having grown up New York, he knew it well and used his knowledge of the city to plan its fictional counterpart, sprinkling in familiar neighborhoods, parks, civic buildings, monuments, landmarks and transit infrastructure.
The city took shape in a week and, after some testy exchanges with editors and few back-and-forth faxes, Gotham's rough coastline was finalized less than two months later. Brown's final hand-annotated map of Gotham City included numerous bridges and tunnels ready to be dynamited by the U.S. government, as well as a few forgotten steam tunnels that might be useful to a crimefighter and his allies. Brown didn't just design the city; he designed an implicit history that writers are still exploring….
While a map may seem like a small thing, especially for a fictional city, it really does make Gotham feel like more of a real place. So why don't more comics map out their cities? Why isn't there a definitive Metropolis or a definitive Star City? Besides the amount of work it takes, Brown thinks the imposition of an official map might just be too limiting for some writers and artists. "If a writer wants Batman to face Croc on a glacier-bound treehouse for mutants—then that's what he writes and gets drawn. If, the next month, Batman is now chasing Harley Quinn at a 24-Hour Endurance Sports Car Race Track—poof, there it is. All right in Gotham City. Put in a better way, it is about allowing the writers to have their freedom."
Be sure to read the rest of the article at Smithsonian, where you can also see the various iterations of the maps.