From 2000 to 2005, the United States lost more than 46,000 square miles of forest. That's about the size of Pennsylvania and is about 6% of the nation's forested land. The Southeast United States experienced the most forest loss, some of which lost more than 10% of its forest. To determine how much of forest land was lost, this study used satellite images to measure the forest loss around the world. The study, which appears in the Proceedings of the National Academy of Sciences, found that the forest loss was the result of both human and natural causes.
Source: USA Today