"The rise of New York in the early nineteenth century is the result of technological changesthat moved ocean shipping from a point-to-point system to a hub andspoke system; New York's geography made it the natural hub of thissystem. Manufacturing then centered in New York because the hub of atransport system is, in many cases, the ideal place to transform rawmaterials into finished goods. This initial dominance was entrenched byNew Yorks role as the hub for immigration. In the late 20th century, NewYorks survival is based almost entirely on finance and business services,which are also legacies of the port. In this period, New Yorks role as ahub still matters, but it is far less important than the edge that density andagglomeration give to the acquisition of knowledge."
[Editor's note: The link below is to an academic journal article (2 MB PDF).]
Thanks to Jon Cecil