714 Rapid industrial expansion. [i890- It is unsafe, however, to place much dependence on such calculations, while the comparison of different periods according to the value of products may give results very different from those reached by a comparison of quantities. A few figures, however, may be given to indicate the surprising growth of the last half decade. The production of coal, which had already surpassed the amount of British production in 1899, increased by 1902 to 293,000,000 (short) tons, an increase of 75,000,000 tons in four years, and of 140,000,000 in ten years. The production of pig-iron increased 90 per cent, between 1897 and 1902, and reached a total of over 17,000,000 tons in the latter year, while steel production increased to about 15,000,000 tons ; the product in both cases being greater than the combined output of the United Kingdom and Germany. In the textile industries the progress has been continuous, but by no means so striking as in iron and steel. The United States now consumes a larger quantity of cotton than the United Kingdom, although this is far from indicating that British supremacy in the cotton industry has been threatened, since the large consumption in the United States is due to the great amount of coarse spinning. The number of spindles at work in the United States in 1900 was only 40 per cent, of those in Great Britain, though more than twice the number used in any other country. Among the textiles the most rapid advance has been made in the manufacture of silk, the product of which is now worth more than $100,000,000, and gives the United States the second place in that industry, but a little behind France. It is not possible to describe the growth of different industries in detail, but a few general statements may be given. The census reports establish fifteen groups of industries, of which the four most important in order are food and kindred products, iron and steel, textiles, and lumber and its manufactures, in each of which the product is valued at over $1,000,000,000. Among these the greatest increase during the decade has been in iron and steel. Among the other groups, that of metals and metal products other than iron and steel shows an increase of over 100 per cent., and a total value of $748,000,000. A special group consists of vehicles for land transport, and shows an increase of 50 per cent, over 1890, and of 396 per cent, since 1880. Other marked increases are in iron and steel shipbuilding, which has risen from about $40,000,000 to over $85,000,000 ; and wood-pulp and paper, with an increase of 61 per cent, over 1890, and a total value of over $127,000,000. Other general marks of progress may be noted. The estimated horse-power used in production rose 90 per cent, between 1890 and 1900, from less than 6,000,000 to over 11,000,000. The railroad mileage increased in the decade ending 1902, from 171,563 to over 200,000 miles, and constitutes more than 40 per cent, of the total mileage of the world ; while traffic increased from 88,000,000,000 to
