There are two semi-isolated permanent populations in the eastern part of the United States. This first is a population along the West Virginia border in the Allegheny Plateau. The second population is in the higher elevations (>4000 ft) of the southern Appalachian Mountains of western North Carolina, eastern Tennessee, and southwestern Virginia. Although there are abundant populations in the Northern and Western Regions of North America, in some counties of North Carolina, it is currently listed as a threatened species due to a decline in suitable habitat. This is due to loss of boreal forests from hemlock woolly adelgid, logging, and pollution.