Although the Alleghany Mountains were a temporary obstacle to the westward advance of the early colonists, the check was not more than sufficient to insure that the Atlantic slope should be fairly well occupied before population spread westward. Along the St. Lawrence and the Ohio, and up the course of the Mis sissippi, explorers and settlers pushed their way over natural water-routes, still utilized by their successors. The deep Hudson River 1 To those who are students of both geology and economics it is interesting that the Hudson is a partially " drowned " river and that it owes its commercial importance to a slight subsidence and submergence of the old river valley.
with the magnificent harbor at its mouth ; the Delaware and Potomac with their broad estu aries ; the rolling, unbroken prairies of the central states ; the unique system of fresh water lakes ; the gradual rise of the entire continent toward the west, as if to encourage directly a rapid colonization by Europeans ; the rivers and mountains extending from north to south, as if to insure the social and political unity which differences of climate and natural productions might otherwise render difficult, all these geographical characteristics of the continent enter as determining elements into her economic environment. The commerce and industry of America, her art and letters, her politics and laws, her life and thought, will ultimately be influenced by her climate and soil and geographical contour.
Reference must be made, in closing this chapter, to the possession of what are known as mineral resources. In the popular mind the importance of these resources to national welfare is usually exaggerated, but it cannot be denied that their presence exercises a great influence upon the character of the national industry, and they must therefore be reckoned as a part of the environment.
Iron ore deserves the first rank among the mineral resources of the earth, because of its wide distribution and its high place in the history of the arts. It is the most " useful " of the metals, if in assigning their relative rank we consider only the number of uses to which they may be put and the essential relation of such uses to the most primitive wants of man. Copper, tin, and lead are useful in the same sense of that word. Silver and gold possess qualities that have given them a unique relation to man's welfare from very early ages. Well adapted to many important industrial uses, they are also prized for purposes of personal adorn ment, and in later stages of social development they are found to be better suited than any other substances to serve as a medium for the exchange of goods.
The environment provides, besides the min eral deposits, the results of animal and vege table life. Such things as are provided spontaneously in a form capable of satisfying man's wants, are to be regarded as products of the environment rather than of man's eco nomic activity. The most conspicuous example is coal, which, although a vegetable product of past ages, yet from an economic point of view resembles mineral deposits more closely than it does ordinary vegetable products.
It will be more convenient to regard the environment as providing in general only the forces and crude materials of industry, and to treat all vegetable and animal products, together with the utilization of mineral re sources, in a later chapter.