They can be found in any area that gives shelter, solitude and food resources. The NE is the most common and abundant of these. But far from limited to there.
There is activity about an hour from my house but the locals are very protective of them. Some do true expeditions (for a few hundred bucks of course) each year. of the three trips I know of, two were uneventful but one has tracks, howls and answered tree thumping.
Though I want proof of their existance (if only to stop the ribbing of my belief in them) I wish no harm of them and generally they leave you alone unless they feel threatened and even then give PLENTY of warning first. Warnings consist of rock throwing, nasty smells, howls and something I can only describ as a physic fear. As a victum of this fear effect I can only say it is overwhelming and unexplainable.