In about 1700, forests in the southeastern United States and other parts of 
eastern North America began to recede. Trees were felled for many purposes, 
including the clearing of land and the gathering of building materials and 
fuel. As recently as the 1920s, the tanning industry in the Great Smoky 
Mountains used the bark of hemlock trees, far left, leaving the logs to rot 
once they had been stripped. Increased mechanization quickened the pace of 
forest destruction, and by the end of the last century, many lumbering 
operations, such as the sawmill in Greenville, Mississippi, left, were served by 
railroads. George Inness's 1855 painting The Lackawanna Valley, below, 
shows clearly how the combined impacts of settlements, cultivation, and 
railroads reduced the vast forests to little more than patchy remnants. 
National Gallery of Art. Washington 
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