My grandfather, who thought that the pun was the highest form of humor, imparted to me a love of words and wordplay during numerous games of Scrabble in my early years. So as I followed that interest this morning I stumbled upon the definitive answer to an old question: “Why is New York called the Big Apple?”
There are numerous false etymologies circulating on the web, but John J. Fitz Gerald was the man who first popularized the phrase. He is pictured hatless in this photo:

"The Big Apple" was the catchphrase of New York Morning Telegraph track writer John J. Fitz Gerald in the 1920s. He admitted this twice and it was the name of three of his columns. He picked up the term from African-American ("dusky" he called them) stable hands at the Fair Grounds racetrack in New Orleans, probably on January 14, 1920.
Fitz Gerald's first New York Morning Telegraph "Around the Big Apple" column, on February 18, 1924, proudly declared:
The Big Apple. The dream of every lad that ever threw a leg over a thoroughbred and the goal of all horsemen. There's only one Big Apple. That's New York.
The "Big Apple" racing circuit had meant "the big time," the place where the big money was to be won. Horses love apples, and apples were widely regarded as the mythical king of fruit. In contrast, the smaller, poorer tracks were called the "leaky roof circuit" or "bull ring" tracks.
"The Big Apple" became the name of a club in Harlem in 1934, and Harlem itself was referred to as "the Apple" at this time. A club in Columbia, South Carolina also took the "Big Apple" name, and it was here that 1937's short-lived national "Big Apple" dance craze began.
"The Big Apple" was revived in the 1970s by Charles Gillett, president of the New York Convention and Visitors Bureau.
The origins of "the Big Apple" were solved in the 1990s by Gerald Cohen and Barry Popik. A "Big Apple Corner" street sign was dedicated in 1997 at West 54th Street and Broadway, where Fitz Gerald last lived.
http://www.barrypopik.com/

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