They show a map in the Pilot when Clark (he is not Superman yet, he doesn't have the suit) flies to Shanghai, and that makes it look like Metropolis is somewhere in North-east Pennsylvania, maybe not far from Scranton.
However in "Return of the Prankster" there is a map at the poor company that Griffin is messing with, and that really looks like it is a section of New York City.
Then there is the "Night Before Mxmas" where the bar tender is shocked to learn the 5th dimension is worse than Jersey. This establishes that Metropolis is not in New Jersey.
Also in I think it was "Ordinary People" Clark goes to deal with a nuclear problem in Philadelphia and the bad guys try to kill Lois while he is away. I am not sure that tells us much beyond that Metropolis is not Philly.
On the other hand at least in the script for "Man of Steal Bars" Lois mentions that it is much colder in New York. They did change a lot between the script we have an actual publication, moving it from December to November and from over 100 degrees to in the 90s, but I think they did keep the mention of New York.
Actually I went and watched through that point, and Lois does say "its 12 degrees in New York, they have 8 inches of snow in Chicago and were having a run on sun block."
So it does appear at some level New York is elsewhere. That does not mean that Metropolis is not in other ways a New York equivalent.
