The Allegheny Mountains form a high region running from the Elk (4,345 feet) and Gauley (4,571 feet) mountains in Pocahontas and Randolph counties northward to the state line. The Alleghenies are marked on the east by the line of Back Allegheny (4,840 feet), Shavers (4,193 feet), and Allegheny Front (3,200 feet) mountains, and on the west by the line of Rich (3,660 feet), Laurel (2,915 feet), and Chestnut (2,600 feet) mountains. The Allegheny Mountains make up about 12 percent of West Virginia's total area, mostly in Preston, Tucker, and Randolph counties.

The Allegheny Mountains are higher than the Allegheny Plateau to the west. The mountains themselves are plateau-like with closely spaced broad summits and flat horizons. The mild folds of the bedrock throughout the mountains generally control the erosional forms, producing a weak, trellis-like stream pattern of narrow valleys similar to the well-developed broad valleys of the Ridge and Valley Province to the east. In the north the valley strips are some 300 to 500 feet deep, and in extreme cases along the Cheat River up to 1,000 feet deep, whereas in the broken ranges in the south valley depths of 1,000 feet are not uncommon.

The surface of the region consists of rolling to steeply ridged hills. In Preston and Tucker counties the average elevation is close to 3,000 feet, and Randolph, where two-thirds of the county is in slopes steeper than 20 percent, may be referred to as entirely mountainous.

Settlement in the Allegheny Mountains dates from 1753, when the Eckarly brothers settled on the Cheat River near Kingwood. In the river valleys and on the more gentle slopes the early settlers raised livestock, buckwheat, corn, and other essentials of a pioneer life. The first real economic boost came when the Baltimore & Ohio Railroad crossed the region in 1852. By the turn of the next century, the timbering of virgin stands of red spruce above 2,500 feet elevation and of northern hardwoods, between 2,000 and 2,500 feet, and coal mining fueled a boom economy. Elkins (1,920 feet), Kingwood (1,863 feet), Terra Alta (2,559 feet), Parsons (1,652 feet), Piedmont (935 feet), and Davis (the highest town in West Virginia at 3,100 feet) are the largest towns in the mountains.

Elevation has a direct effect on the climate of the Allegheny Mountains. The January average temperature of 28 degrees F. at Terra Alta is the lowest in the state. The mean annual snowfall for the region is about 60 inches, with more than 100 inches falling on the southern margins of Cheat Mountain and Back Allegheny Mountain at the Snowshoe ski resort. Another fact of the Allegheny region is heavy rainfall. Pickens, located at about 2,700 feet on the western slope of Turkeybone Mountain, has an average annual rainfall of about 70 inches.

At the rugged and high southern end of the Allegheny Mountains are the headwaters of the Gauley, Elk, Little Kanawha, Tygart, Cheat, and Greenbrier rivers. The Cheat River flows northward through the heart of the Allegheny Mountains to a confluence with the Monongahela just north of the state line in Pennsylvania.

The Seneca Trail, one of the principal Indian trails in North America, followed Seneca Creek across the Allegheny Front, then crossed in succession Spruce, Rich, Middle, Shavers, and Cheat mountains to the present location of Elkins. This is the route now followed by U.S. 33 and State Route 55. With elevations of 3,000 to 3,500 feet not uncommon, it includes some of the highest and most scenic stretches of highway in West Virginia.

From southern Preston County, U.S. 219 crosses Backbone and Cheat mountains, follows the Tygart Valley, then crosses through gaps or skirts around the edges of Elk (4,345), Valley (3,846 feet), Middle (3,993 feet), Gauley (4,571 feet), Red Lick (4,686 feet), and Elk (3,760 feet) mountains before exiting the region. (There are two Elk mountains, one in Randolph County and the other in Pocahontas.) U.S. 50 follows Friendship Gap across Laurel Mountain at about 2,500 feet above sea level. State Route 7 through Terra Alta crosses Briery Mountain at almost 3,000 feet. Farther to the north, the Allegheny Mountains are more plateau-like where Interstate 68 crosses between Coopers Rock and Hazelton. The elevations between these two points average about 2,000 feet, but vary as ridges are crossed.

Several natural recreation areas are associated with the Allegheny Mountains, including the Dolly Sods Wilderness Area, Canaan Valley, Blackwater Falls and Canyon, Snowshoe, and the Monongahela National Forest.