Big Apple
"The Big Apple" was popularized as a name for New York City by John J. Fitz Gerald in a number of horse-racing articles for the "New York Morning Telegraph" in the 1920s. The earliest of these was a casual reference on 3rd May, 1921:
Big Apple
Fitz Gerald referred to the "big apple" frequently thereafter. He explained his use in a column dated February 18, 1924, under the headline "Around the Big Apple":