I don't think it's big enough to be an American crow - wiki says they're about 18 inches.
It was a wild bird, so even the dubious signage at the zoo wouldn't have helped.
I'm more familiar with grackles, which we have in abundance in AZ, but this was bigger.
Bear in mind bird measurements are taken with the bird laid on its back and measured tail-tip to bill-tip, which usually has the effect of giving a bigger measurement than the bird appears in its natural pose.
I'm not over-familiar with US birds, but this definitely looks like a crow of some sort. From the one reference book I have that covers this, American Crow seems a good ID.
The beak looks odd; disproportionately long & unexpectedly curved. Other than this, it looks big enough to be a crow, if that's a normal-size fence it's sitting on. What do other people think?
I just thought the bird looked too big to be a crow.
According to Wikipedia, there are only 4 species of corvids ever signted in New Jersey; the blue jay, American crow, fish crow, and common raven. Its obviously not a blue jay, so that leaves the other three.
I'd come down on the side of an American crow with an unusual shaped bill. I've seen downward curving bills on other American crows, although admittedly not to this degree. The feather colouration is correct for an American crow too.