The Allegheny Mountain Range, informally the Alleghenies, is part of the vast Appalachian Mountain Range of the Eastern United States and Canada and posed a significant barrier to land travel in less developed eras. The Allegheny Mountains have a northeast–southwest orientation, running for about 400 miles (640 km) from north-central Pennsylvania, southward through western Maryland and eastern West Virginia.
The Alleghenies comprise the rugged western-central portion of the Appalachians. They rise to approximately 4,862 feet (1,482 m) in northeastern West Virginia. In the east, they are dominated by a high, steep escarpment known as the Allegheny Front. In the west, they slope down into the closely associated Allegheny Plateau, which extends into Ohio and Kentucky. The principal settlements of the Alleghenies are Altoona, State College, and Johnstown, Pennsylvania; and Cumberland, Maryland.
The High Alleghenies are noted for their forests of red spruce, balsam fir, and mountain ash, trees typically found much farther north. Hardwood forests also include yellow birch, sugar and red maple, eastern hemlock, and black cherry. American beech, pine and hickory can also be found. The forests of the entire region are now almost all second- or third-growth forests, the original trees having been removed in the late 19th and (in West Virginia) early 20th centuries. The wild onion known as the ramp (Allium tricoccum) is also present in the deeper forests.
Certain isolated areas in the High Alleghenies are well known for their open expanses of sphagnum bogs and heath shrubs (e.g., Dolly Sods, Cranberry Glades). Many plant communities are indeed similar to those of sea-level eastern Canada. But the ecosystems within the Alleghenies are remarkably varied. In recent decades, the many stages of ecologic succession throughout the area have made the region one of enduring interest to botanists.
The larger megafauna which once inhabited the High Alleghenies—elk, bison, mountain lion—were all exterminated during the 19th century. They survived longer in this area, however, than in other parts of the eastern United States. Naturalist John James Audubon reported that by 1851 a few eastern elk (Cervus canadensis canadiensis) could still be found in the Alleghany Mountains but that by then they were virtually gone from the remainder of their range. Mammals in the Allegheny region today include whitetail deer, chipmunk, raccoon, skunk, groundhog, opossum, weasel, field mouse, flying squirrel, cottontail rabbit, gray foxes, red foxes, gray squirrels, red squirrels and a cave bat. Bobcat, snowshoe hare, wild boar and black bear and coyote are also found in the forests and parks of the Alleghenies. Mink and beaver are much less often seen.
These mountains and plateau have over 20 species of reptiles represented as lizard, skink, turtle and snake. Some of the icterid birds visit the mountains as well as the hermit thrush and wood thrush. North American migrant birds live throughout the mountains during the warmer seasons. Occasionally, osprey and eagles can be found nesting along the streams. The hawks and owls are the most common birds of prey.
The water habitats of the Alleghenies hold 24 families of fish. Amphibian species number about 21, among them hellbenders, lungless salamanders, and various toads and frogs. The Alleghenies provide habitat for about 54 species of common invertebrate. These include Gastropoda, slugs, leech, earthworms and grub worm. Cave crayfish (Cambarus nerterius) live alongside a little over seven dozen cave invertebrates.