The state of Maine has 10 million uninhabited acres of trees. Altogether, just 2% of the United States is classified as built up.
I read that in A Walk in the Woods by Bill Bryson. It was written in 1998 but I wouldn’t think the figures now are too far off.
The book by Bryson is a personal description of his hiking trip through the Appalachian Trail. He and his out-of-shape buddy go through some amusing experiences. At the beginning of each chapter, he gives a short history of the area, including stories that most of us probably had never heard. There is a lot that can be learn from this book. Bryson is a funny writer.
But I did not have patience to read the entire book because it doesn’t have a plot. The anecdotes are certainly fun to read but since there is no story to follow, I lost interest about half-way.