The United States, in the area of productive land, is second only to Russia. In the area of land actually under cultivation, however, it stands first, with Russia a close second and British India a close third,--the amounts of cultivated land in each of these countries being 293.8 million acres, 279.6 million acres, and 264.9 million acres respectively. These three countries together contain 64 per cent of the 1,313.8 million acres of cultivated land of the world. The United States alone contains 22 per cent of the total cultivated land. The total forest acreage available for commercial purposes is greatest in Russia (728.4 million acres). The United States stands second with 400 million acres and Canada third with 341 million acres. The Chief of Forest Investigations of the United States Department of Agriculture (Letter of Oct. 11, 1919) places the total forest acreage of both Brazil and Canada ahead of the United States. In the case of Brazil no figures are available showing what portion of the 988 million acres of total area is commercially available. Canada with a total forest acreage of 800 million acres has less timber commercially available than the United States with a total forest area of 500 million acres. The iron ore reserves of the world are estimated at 91,000 million tons ("Iron Ores," Edwin C. Eckel. McGraw Hill Book Co., 1914, pp. 392-3). Of this amount 51,000 millions are placed in Asia and Africa; 12,000 million tons in Europe, and 14,800 million tons in North America. The United States alone is credited with 4,260 million tons or about 5 per cent of the world's supply. The United States Geological Survey (_Bulletin_ 666v) estimates the supply of the United States at 7,550 million tons; the supply in Newfoundland, Mexico and Cuba as 7,000 million tons, and that in South America as 8,000 million tons as against 12,000 million tons for Europe. This estimate would give the United States alone 8 per cent of the iron ore of the world. It would give North America 15 per cent and the Western Hemisphere 25 per cent, as against 15 per cent for Europe. Iron ore furnishes the material out of which industrial civilization is constructed. Until recently the source of industrial power has been coal. Even to-day petroleum and water play a relatively unimportant rôle. Coal still holds the field. The United States alone contains 3,838,657 million tons--more than half of the total coal reserves of the world. ("Coal Resources of the World." Compiled by the Executive Committee, International Geological Congress, 1913, Vol. I, p. XVIII ff.) North America is credited with 5,073,431 million tons or over two-thirds of the world's total coal reserves (7,397,553 millions of tons). The coal reserve of Europe is 784,190 million tons or about one-fifth of the coal reserves of the United States alone.