Why was the rise of new york city so phenomenal? what forces combined to make it america's leading city?

All of the first great American cities were seaports or major river ports. The three largest northern seaports in the early US were Boston, New York and Philadelphia.  As the population of the U.S. grew and moved westward,it became more important for goods and merchandise to be moved easily from the seaport westward into the interior of the continent.