(1) The Northeastern, comprising the states of Vermont, Massachusetts, Connecticut, New York, New Jersey, Pennsylvania, Maryland, and Ohio, supplies a little more than five per cent. of the iron mined in the United States. (2) The Southeastern, containing Virginia, West Virginia, eastern Kentucky, and Tennessee, North and South Carolina, Georgia, and Alabama, gives us twelve per cent. of our iron. (3) The Lake Superior district, containing the northern parts of Michigan, Minnesota and Wisconsin, supplies more than eighty per cent. (4) The Mississippi Valley district contains western Kentucky, and Tennessee, Iowa, Missouri, Arkansas and Texas. This region furnishes less than half of one per cent. of the total supply. (5) The Rocky Mountain district contains Montana, Idaho, Wyoming, Colorado, Utah, Nevada, New Mexico, Arizona, western Texas, Washington, Oregon and California; and all this great region now supplies but a little more than one per cent. The official report, which is as thorough as can be made but is naturally subject to mistakes, gives the amount of available iron, that is, that which can be mined under present conditions, as nearly five billion tons. Let us see how long this may be expected to supply the demand. Before 1810 the amount of iron ore produced was so small as to be scarcely worth considering. From 1810 to 1870 a little less than fifty million tons were mined, from 1870 to 1889 nearly 154,000,000 tons, and from 1889 to 1907, 475,000,000 tons, or altogether nearly 680,000,000 tons. The production has been found to double itself about every nine years. In 1907 alone it was 52,000,000 tons or about one-thirteenth of all that has been mined. In 1880 we used 200 pounds of pig-iron for every man, woman, and child in the country; in 1890, 320 pounds; in 1900, 390 pounds, and in 1907, 696 pounds. According to the rule of increase, by 1916 we shall be using 104,000,000 tons a year; by 1925, 208,000,000, and by 1934, 416,000,000 tons, and if the same rate of increase should continue, by 1940 we should have required for our use in the meantime, six billion tons. But we have less than five billion tons of what is now classed as available ore, which means that before that time (when the school-boys of to-day are business men) we should have exhausted all our good and cheap ore, and be obliged to depend only on the low-grade ores, the cost of which will be very great. Unlike coal, the forests, and the soil, there is no great and entirely useless waste of iron. But the uses of iron are so many and so varied, and the supply of high-grade ores which can be cheaply mined is so small in proportion to the needs of the future, that we should in all ways lessen the drain on it by substituting other cheaper and more plentiful materials when possible.