He loses a lot of credibility with this statement. What I guess he means is the land is not occupied by people. But if you take a look the land is heavily used for grazing, timber, mining. I've flown over and driven over the US quite a few times and it really depresses me. The Mississippi is turned into a big drainage ditch. From the ground I see cattle grazing everywhere and they have huge effects on the original ecosystem. The ranchers that have been protesting out west about grazing on government land have gotten in trouble for burning native shrub so it can be replaced with grasses better for cattle. Even historically there has been much fighting over land in the west, they were called the range wars. Montana was the most famous, but there has been lots of other wars over water, fences and sheep vs cattle.