=The Appalachian Region.=--The middle and southern Appalachian region has become the most important centre of iron and steel manufacture in the world. This great development has resulted from several causes, the chief being the existence of coal and unlimited quantities of iron ore on the one hand, and unusual facilities for cheap transportation on the other. There are practically three areas of steel manufacture--one along the Ohio River and its tributaries in western Pennsylvania; another is situated along the south shores of Lake Erie and Lake Michigan; the third includes the Birmingham district in the southern Appalachians. The steel-making plants of the Ohio River are located with reference to the transportation of their products, and therefore are built usually alongside the river. The coal or coke is commonly shipped in barges of light draught; the manufactured products are carried by rail. The greater part of the ore is brought from the Lake Superior region. It is shipped at a very small cost from the ore quarries to the lake-shore, and by rail from the lake-shore to the manufacturing plant. In order to avoid heavy grades the ore railways are also built along the river-valleys. [Illustration: STEEL MANUFACTURE--ERECTING SHOP OF THE BALDWIN LOCOMOTIVE WORKS, PHILADELPHIA] Some of the various steel-making plants are equipped for the manufacture of building or "structural" steel, others for rails and railway equipments, still others for tin-plate, or for wire, or for tool steel. In a few mills armor-plate and ordinary plate for steel vessels form the exclusive product. The diversity of the product has led to the organization of great corporations, each of which controls half-a-dozen or more plants, the transportation lines necessary to carry the product, the ore quarries, and the fuel-mines. The wonderful development of the steel industry in the United States is due to the use of labor-saving machinery, and to the superb organization. The wages paid for labor are higher than those paid in European steel-making centres; the cost of living is not materially greater. The price of steel rails, which in 1880 was forty-eight dollars per ton, in 1900 was about twenty dollars per ton.