Iron smelting, made possible by abundant supplies of ore and of hardwoods for the furnaces, became important in the 18th cent. In the 19th cent., after the Bessemer process made the use of its great bituminous deposits economical, Pennsylvania quickly emerged as the nation's leading steel producer, but the industry has since declined dramatically. Another Pennsylvania resource, anthracite coal, found in the northeast, long made the state a dominant force in American railroading. In the early 21st cent., shale gas has driven a drilling boom in N and W Pennsylvania. Heavy industry has declined in general, but the state still manufactures metal products, transportation equipment, foodstuffs, machinery, chemicals, and a wide variety of plastic, rubber, stone, clay, and glass products.
The Pittsburgh and Philadelphia metropolitan areas, situated at opposite ends of the state and dominating the commercial and industrial life of their regions, present startling contrasts in production and culture. Other leading cities are Allentown, Bethlehem, Erie, Reading, Scranton, and Wilkes-Barre.
Agriculture is concentrated in the fertile counties of the southeast, and prized farmlands lie in the Great Appalachian Valley, rich with limestone soils; here the Pennsylvania Dutch farmer built a culture that is identified with the bountiful agrarian life. Principal agricultural products include dairy products, cattle, hay, corn, wheat, oats, mushrooms, poultry, potatoes, and fruit.
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