From the Village Voice:
While the city has had a number of nicknames over the years, no official second appellation exists. Now, one elected official is pushing the City Council to designate
“Gotham City” as New York City’s chief nickname just in time for the summer release of "Batman: The Dark Night."
Councilman Goes to Bat for 'Gotham City'
Queens Councilman Hiram Monserrate, who counts Batman as one of his childhood heroes, views his Gotham City pitch as a tourist lure. “I see that as a marketing tool, ‘Come visit the real Gotham City,’ taking advantage of this movie which will be one of those gate-breaking, record-selling movies like it always is,” he said.