FIGURE 18.1 Iron and Steel Production, 1870–1900 Iron and steel production in the United States grew from nearly none in 1870 to 10 million tons a year by 1900. The secrets to such a great increase were the use of the Bessemer process and vertical integration, pioneered by Andrew Carnegie. By 1900, Carnegie’s mills alone produced more steel than all of Great Britain. With corporate consolidation after 1900, the rate of growth in steel proved even more spectacular.