Why is New York City also called “the Big Apple”?

Question

I have heard many times people say the Big Apple to mean New York City.

What is the origin of this nickname?

Answer 1

Wikipedia offers some interesting reading on the subject, but my understanding is that nobody still knows for sure.

The earliest citation for "big apple" is the 1909 book The Wayfarer in New York, by Edward Martin, writing: "Kansas is apt to see in New York a greedy city. . . . It inclines to think that the big apple gets a disproportionate share of the national sap". [The American journalist] William Safire considered this the coinage, but the Random House Dictionary of American Slang considers the usage "metaphorical or perhaps proverbial, rather than a concrete example of the later slang term", and [Barry] Popik [, an American amateur etymologist,] likewise does not consider this the coinage.

Answer 2

Apples are commonly grown in New York State. It is the state fruit and a major export.

So, Big Apple would compare the city to upstate. Imagine a map with the cities marked as apples.