This fact, that only about one-half of the world's international trade ever leaves the con tinent of its production, suggests a further in-, quiry, as to the share of the total world's products which enter international trade and the share which is exchanged between conti vents. This, however, cannot yet be deter mined for the entire world, or indeed for many of the countries, because of the fact that the facilities of measuring the value of all the products of the various countries are in most cases insufficient to render available accurate figures as to the total value of the produce and thus determine the share entering international or inter-continental commerce. In the case of the United States, however, it is estimated from official figures of the production of the various classes of articles, agricultural, manu factures, mines, forests, fisheries, etc., that the value of the total products in 1913, the latest normal year, was about $40,000,000,000, of which a little more than 6 per cent was ex ported, and of this but about two-thirds, or approximately 4 per cent of the total passed to other continents.
Attention has been called to the fact that a considerable part of the international commerce of the world is the interchange between the climatic sections, the temperate zones and the tropics. The strictly tropical sections now ex port about $3,500,000,000 worth of merchan dise annually, and import about an equal quan tity, and most of this is inter-continental trade. Their chief exports are sugar, rice, coffee, tea, cacao, rubber, silk, cotton, jute, hemp, sisal, hides, gums, tobacco and fruits, and it happens that certain of the important minerals of the world, notably tin, nitrates and much of the gold, silver, lead and copper are also mined in that section. Practically all of these go to the north temperate zone. This tropical belt could produce and supply much more of these im portant articles, all of which are demanded by the temperate zones for food and manufac turing, if they had railroad facilities to bring their possible products to the water's edge, where the temperate zone countries gladly send their vessels to get whatever the tropics have to offer. Thus about $3,500,000,000 worth of the
F0,000,000,000 worth of merchandise entering international trade is now produced in the tropical belt, and most of it sent to the tem perate zones, a large part of that trade being inter-continental while nearly all of this trop ical production exported is paid for in the manufactures, breadstuffs and meats of the north temperate zone, and is thus chiefly inter continental.
The remainder of the inter-continental trade, aside from that of the tropics is the inter change of the foodstuffs and manufacturing material of the newly-developed areas for the manufactures of those which have great manu facturing systems, Europe, the United States and Japan. The countries of the south tem perate zone send their fresh meats in refriger ating vessels across the equator to the mar kets of Europe, where they arrive in perfect condition for consumption, also their wool and grains and hides and fibres and coffee and tea and sugar and fruits and metals, and most of these are received by the north temperate zone and paid for in manufactures, chiefly the prod ucts of Europe and the United States, for prac tically all the factory products of the world are produced in the north temperate zone, and chiefly in Europe, the United States and Japan. The total value of the manufactures produced by the factories of the world is nor mally about $70,000,000,000 per annum, of which approximately $7,000,000,000 or 10 per cents enters international trade, the other 90 per cent being consumed in the countries of pro duction. Of this $7,000,000,000 worth of manu factures entering the international trade of the world the United States, in normal years, sup plies about $1,030,000,000 worth, though the great increase in our exports of manufactures under the stimulus of the war gives reason to hope that we may permanently retain a larger share of the world's trade in manufactures after a return to peace conditions.