"Tanning started out as a small cottage-industry devoted to farmers processing hides for local consumption. By the middle of the nineteenth century, however, the increasing demand for shoes, harnesses, saddles, and belting for the nation's factories had transformed the leather business into the nation's 5th largest industry. Like the wood pulp industry, competition eventually led to the consolidation of many of the tanneries and the formation of large companies like the US Leather Company. In 1901, the US Leather Company controlled 75 percent of Pennsylvania's lumber stumpage. By 1910 its successor, the Central Leather Company, was one of the ten largest firms in the United States. The large sole leather factories of northern Pennsylvania required enormous quantities of hemlock bark. An the end of the century the larger operations were utilizing 10,000 cords of hemlock bark a year. (or 40,000 trees). Since the tanning of each hide required 12 times its weight in bark, it was advantageous for the tanneries to be located close to the source of the bark.... The sole leather industry was another case where America's old-growth forest furnished the raw materials for a major extractive industry. By 1870, the large supply of hemlock in the Catskill Mountains in New York had been liquidated and the major center of activity shifted to the High Allegheny Plateau region of southern New York and northern Pennsylvania. Armed with axes and spuds, instruments for removing the bark, large armies of men moved from ravine to ravine, methodically eliminating the hemlock. Unfortunately, hemlock regenerates very slowly following its removal. Pennsylvania's 'inexhaustible' supplies of hemlock lasted into the 1920's and demise of the large hemlock-based tanning industry followed shortly thereafter".