The ecoregion consists of four separate blocks of mixed forest surrounded by lower lying areas of hardwood forest as follows: the Northern Allegheny Plateau in New York State and Pennsylvania including the Catskill Mountains, the Poconos, the Finger Lakes and French Creek areas; areas of the north and central Appalachians; the western Allegheny Plateau in western Pennsylvania and Ohio; and the upland plain around Lake Erie and Lake Ontario.