Why is New York America's Largest City?

The rise of New York in the early nineteenth century is the result of technological changes that moved ocean shipping from a point-to-point system to a hub and spoke system; New York’s geography made it the natural hub of this system. Manufacturing then centered in New York because the hub of a transport system is, in many cases, the ideal place to transform raw materials into finished goods. This initial dominance was entrenched by New York's role as the hub for immigration. In the late 20th century, New
York's survival is based almost entirely on finance and business services, which are also legacies of the port. In this period, New York’s role as a hub still matters, but it is far less important than the edge that density and agglomeration give to the acquisition of knowledge.