much of the land so employed has no other important use. Expenditures in connection with organized outdoor games run into large figures, but the amount of physical materials used is relatively small. The same is true with respect to such activities as fishing, boating, hunting, hiking, and skiing. However, the bulk of the outlays for the use of transportation facilities goes to cover the costs of metal and fuel resources used in railroad trains, street cars, buses, taxicabs, and airplanes.

As much as one third of the total expenditures included in this general category in 1946 went for private automobile transportation. As incomes expand, the percentage spent on automobiles may be expected to show a strong relative increase. Such expenditures constitute direct outlays for steel, rubber, and other materials used in the construction and maintenance of cars, and for gasoline and oil required for their operation. The railroads, highways, buildings, and other physical structures involved in the provision of all types of recreational facilities would likewise impose direct drafts upon underlying mineral resources. The adequacy of our metal and mineral supplies and fuel and energy resources will be considered in Sections VII and VIII below. The other materials involved are considered here.

In recent years, many automobile accessories formerly made of natural materials are being replaced by synthetic products. How far this process of substitution can be carried will depend largely upon relative cost trends, which will doubtless progressively favor the substitute materials. Under the impetus of war necessity, large quantities of synthetic rubber tires were produced in this and other countries. While not yet as satisfactory as those made from natural rubber, it is contended by some that

in time they may be superior-"non-skid, punctureproof, and good for 100,000 miles."13

The materials used in books, magazines, newspapers, sheet music, musical instruments, boats, plants and flowers, etc., present a less difficult problem. Newsprint, as already indicated, can be indefinitely expanded." Pleasure boats are already being built of waterproof synthetic materials that will not warp, scratch, or splinter, the compound curves of which are prefabricated in convenient sections. The costs here are still high, but should gradually decline as synthetic processes are improved. Plastic materials are also now being used extensively in connection with musical instruments, and with improved results. Musical instruments over the centuries had been severely circumscribed in form and tonal combinations as a result of limitations imposed by the use of natural substances alone. Freed from such limitations by synthetic materials, the music of the future can be adapted more readily and completely to satisfying recreational and aesthetic desires.15 Developments in radio, television, and other electronic instruments are also contributing to the fuller satisfaction of such desires.

VII. METAL AND MINERAL RESOURCES

Discussion of the underlying metal and mineral requirements for so vast an expansion of production as that under contemplation was postponed in earlier sections in order that the entire problem might be considered in one place. Fabricated metals are required in a large way in the production of certain types of consumer goods, such as automobiles, houses, and household appliances. The greatest use of these metals, however, is in capital goods, such as industrial plants, commercial structures,

industrial and agricultural machinery, and transportation and public utility equipment. These metal products require the use of iron, lead, copper, zinc, and magnesium ores, and a wide range of lesser metallic minerals. Nonmetallic minerals such as sulphur and phosphorus are also extensively used by industry. Would the underlying mineral resources, or substitutes therefor, be adequate to meet the indicated requirements?

Numerous minerals are found in great abundance in the United States. Among these are molybdenum, magnesium, calcium, sodium, potassium, sulphur, and phosphorus. The unique deposit of molybdenum in Colorado will last hundreds of years. Magnesium is now commercially available from sea water-an inexhaustible resource. Calcium, sodium, and potassium salts are found, in seemingly limitless quantity, in beds deposited by the sea. Sulphur is closely associated with such sedimentary deposits and seems plentiful enough for all probable needs. Huge quarries of phosphate rock likewise appear ample to meet both industrial and agricultural requirements for phosphorus.

Present deficiencies in certain important minerals can be surmounted.

In the case of a number of important minerals, the United States is substantially dependent upon foreign sources of supply. Among these are nickel and tin, used in alloys and in electroplating; manganese, indispensable in deoxidizing, desulphurizing, and recarbonizing steel; cobalt, essential in the manufacture of high heat-and corrosion-resisting steels and other alloys; and asbestos, used for heat-resistant purposes in many products.

Such important metals as copper, lead, and zinc may

be placed in an intermediate category. The United States once seemed adequately supplied with these minerals, but two world wars exacted a heavy toll. Accordingly, in recent years we have been partly dependent on foreign sources of supply.

Looking forward, several means of overcoming present deficiencies should be borne in mind:

First, systematic exploration will still undoubtedly disclose important new sources of supplies within the United States. This is the view of the Geological Survey and the Bureau of Mines, which point out that only a small part of the ore-bearing regions has thus far been thoroughly explored.

Second, imports from other countries may continue to meet our needs. Fortunately, adjacent Canada is one of the world's richest ore-producing regions and is even now the greatest metal-exporting country in the world, ranking first in the production of nickel and platinum, second in uranium and asbestos, third in cobalt, copper, mercury, silver, and zinc, and fourth in lead. The far north of this continent, including Labrador and Alaska as well as Northern Canada, appear, on the basis of preliminary surveys, rich in promise with respect to such metals as iron, tin, tungsten, lead, chromium, mercury,' and titanium. New mineral discoveries are also being made in South America.

16

Third, technology in laboratories and pilot plants is constantly developing methods for producing manganese, chromium, titanium, and other metals from lowgrade domestic ores. Moreover, scientific advances are making possible the ready substitution of one metal for another, as aluminum for copper and steel, and manganese for nickel, and the development of new alloys, such

as titanium with aluminum, magnesium, and iron.

Fourth, chemical discoveries make possible the substitution of synthetic materials for natural mineral substances. It has been demonstrated that most of these synthetic products are as satisfactory as natural minerals, while in some cases they are distinctly superior.

We do not wish to suggest that no difficulties will ever arise with respect to one or more of the mineral products here under discussion. There is, however, good reason for believing that the combined results of systematic exploration, technological progress in the mining and use of materials, and chemical advances, can furnish a vast expansion in the supply of these materials, without increasing unit costs.

The crucial problem is the adequacy

of iron and steel resources.

Modern industrialism has been built primarily on foundations of iron and steel. The chief mineral involved is iron ore, though coke and limestone are also important. Since the supply of limestone is abundant it requires no special consideration here. The United States has been self-sufficient with respect to iron ore and coke. However, because of the enormous consumption in recent decades, and especially since 1940, much concern has been expressed over the possibility that existing reserves might be nearing exhaustion.

To the end of 1943 as much as 2,125 million tons of high-grade ore-containing as much as 50 per cent iron -had been mined in the United States, chiefly in the Mesabi range of the Lake Superior region. The remaining "measured and indicated” reserves of such ore are estimated at 1,626 million tons. Meanwhile, the produc