The coast is about the only part of Maine that is inhabited. That particular dark green area is largely remote, quite harsh, and has very little infrastructure.

The coast is about the only part of Maine that is inhabited. That particular dark green area is largely remote, quite harsh, and has very little infrastructure. North and west of there is the tiny sliver of inhabited Quebec, then go much further beyond and you're in some of the harshest, most remote land in North America. If you're interested in what the area looks like, check out the Trans-Taiga Road as well as the (less remote) James Bay Road.