In a large country like the United States the value and importance of the trade and commerce among the various sections are very great. Each section specializes in a few products, thus creating surpluses which find their way into every other section. The best evidence of this movement is the enormous freight traffic of our railroads. Wherever we go we see trainload after trainload of goods moving in all directions: food eastward, manufactured goods westward, wheat southward, cotton northward. A hasty examination of the food and furnishings even of a modest home will show the significance of our inter-regional trade. Four everyday articles of food - sugar, salt, flour, and fruit - may represent four widely separated regions of the country. Yet because they are so common we are likely to underestimate the complexity of an industrial organization that places them on our breakfast table every morning, and to overlook the methods by which every producer is paid for his product.

Foreign Trade of the United States (In Hundreds of Millions of Dollars).