The Role of the City.

As Americans moved westward, new town sites fueled by land speculation appeared on the nation's map. A few of them became what were later called "gateway cities"—centers of commerce where manufactured goods flowed one way (often west or north) and raw materials and agricultural products flowed the other. These urban areas tied the West to the Atlantic market. With Western fields, forests, plains, and deserts at one end and New York and other Eastern ports on the other, the gateway cities brought the two sections of the country together in a vast economic network. New York City evolved into the main center of transcontinental commerce in the nineteenth century. By 1860 New York had one million residents and functioned as the country's foremost port. It likewise served as the center of finance for many Western ventures. New York...