[3][4] The World Wildlife Fund defines the ecoregion as being the northern part of the Appalachian mixed mesophytic forests.

[citation needed] The Environmental Protection Agency defines it as running from west-central Pennsylvania, east-central and south Ohio, north and northwest West Virginia, and a portion of northeast Kentucky.

Coal mining is still active in the Pennsylvania, West Virginia, and Kentucky portions of the ecoregion, and in Appalachian Ohio to a lesser extent.

The heavy cutting favored hardwoods and created massive amounts of coniferous slash, providing ideal conditions for widespread and intense fires.

Repeated fires also tended to reduce the proportion of sugar maple, beech, and other typical hardwoods and increase such species as aspen, pin cherry, sedges, grasses, and honeysuckles.