First “Big Apple” citation in New Orleans: July 17, 1921

New York Morning Telegraph track writer John J. Fitz Gerald (1892-1963) used “big apple” in his columns since at least May 3, 1921. It meant the “big time” of New York racing. In his columns in 1924 and again in 1926, Fitz Gerald stated that he picked up the “big apple” term from “dusky” (black) stable hands at the Fair Grounds race track in New Orleans, Louisiana.
 
“This daughter of Ultimus-Rflex, which raced so well at the Fair Grounds in the colors of R. D. Brown and under the tutilege of Puddin McDaniel, is the only Orleanian of the past winter that has circulated with conspicuous profit and glory as a ‘big apple’” was printed in the New Orleans (LA) Item on July 17, 1921. The “big apple” term does not appear to be about New York, but describes a horse as a “big apple”—a big money-maker.
 
 
17 July 1921, New Orleans (LA) Item, “Fleet ‘Miss’ Has Not Met Defeat This Year” by P. J. Horgan, pg. 5, col. 8:
But the real item of interest in this connection from a New Orleans viewpoint is the success of My Reverie in the Astoria Dinner Stakes. This daughter of Ultimus-Rflex, which raced so well at the Fair Grounds in the colors of R. D. Brown and under the tutilege of Puddin McDaniel, is the only Orleanian of the past winter that has circulated with conspicuous profit and glory as a “big apple.”