I'm amazed that this whole area I'm living in was both deforested and heavily surface mined back then - to the extent that the Clarion River was considered the most polluted stream in PA and was almost lifeless - and it's pretty much recovered now after some massive cleanup efforts and time. You wouldn't guess what it was like by looking around now.

I also like looking at how settlements change across the years; there were "ghost" towns back around where I grew up in Texas, too.