Compared with most other places in the developed world, America is still to a remarkable extent a land of forests. One-third of the landscape of the lower forty-eight states is covered in trees—728 million acres in all. Maine alone has 10 million uninhabited acres. That’s 15,600 square miles, an area considerably bigger than Belgium, without a single permanent resident. Altogether, just 2 percent of the United States is classified as built up.
