Prior to the arrival of William Penn and his Quaker colonists in 1682, an estimated 90percent of what is now Pennsylvania was covered with old-growth forest: over of white pine, eastern hemlock, and a mix of hardwoods. The forests near the three original counties, Philadelphia, Bucks, and Chester, were the first to be harvested, as the early settlers used the readily available timber to build homes, barns, and ships, and cleared the land for agriculture. The demand for lumber slowly increased and by the time of the American Revolution the lumber industry had reached the interior and mountainous regions of Pennsylvania.