Now, that's kind of a ridiculous sign, as most highway signs aren't going to show you a city 800 miles away as the first and only stop on the interstate. If I trundled onto I-94, I'll see distance signs for Benton Harbor and Chicago, or Ann Arbor and Detroit, not New York City or Las Vegas.
Still, it does give us the first real chance in the nu52 to indulge my ridiculous obsession with DC Geography. (Although it is the second time we've been clued in by highway mileage signs while Dick trundlers by on a motorcycle. Is there some rule in the DC stylebook mandating this?)
Of course, we have usual fistful of caveats. A) Highway signs are only an approximation; B) It's driving miles, not as the crow flies; C) Highways, and indeed other "real" cities, may be substantially different in the DC Universe; and D) If the Busiek Hypothesis (that the DC Earth is larger in size than ours, to accommodate all those extra cities and such) then our speculation is really frakked.
Ah, but what's the point of being careful when you're a nerd? So, given that Gotham's ports mean she's on the water, probably on the East Coast (no matter how Nolan tried to trick us in The Dark Knight Rises). So, playing with Google Maps tells us...
Well, not all that much. Being approximately 800 driving miles from Chicago could place us anywhere from southern Delaware (820 miles) to most of New Jersey (Atlantic City--820 miles! Asbury Park--824 miles!!) to parts of Long Island to southwestern Connecticut (New Haven, at 864 miles, is problem as far as a reasonable interpretation of 800 miles will allow).
You could argue for parts of the Maryland coast--but Gotham sure doesn't feel Marylandish to me. Rhode Island and Massachusetts? Right out. (And no, nowhere along the Gulf coast is close to being 800ish miles to Chicago...
So along the Eastern seaboard, above the Mason-Dixon line? I guess we really didn't narrow it down very much at all, did we? Still, I'm going to go with Asbury Park, so we can get the Batman/Springsteen crossover we've all been waiting for.
Ah, well, keep your eyes opened for more clues...