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:
Erie Canal
The Erie made use of the favorable conditions of New York's unique topography, which provided that area with the only break in the Appalachians south of the Saint Lawrence River. The Hudson is tidal to Troy, and Albany is west of the Appalachians. It allowed for east–west navigation from the coast to the Great Lakes within US territory. The canal system thus gave New York a competitive advantage, helped New York City develop as an international trade center, and allowed Buffalo to grow from just 200 settlers in 1820 to more than 18,000 people by 1840. The port of New York became essentially the Atlantic home port for all of the Midwest—because of this vital connection and others to follow, such as the railroads, New York would become known as the "Empire State" or "the great Empire State".