In a lot of places it's not, "our population expanding." In all of the woods around here you find stone walls and building foundations.
In my WV eighth grade history they told us that the state was 90% cleared in the late 1800's. It was 90% forested in 1967 when I took that class and it's probably around 95% now. All the farms and cleared fields around where I grew up are completely grown up and filled with deer, turkey, and yes, bears. When I was a kid there wasn't even a deer season.
I think there are very few places where they are plonking down new neighborhoods and parks in wild territory. I think it's more like historically farmed land that has been allowed to go fallow.