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Major escarpment in the Allegheny Mountains
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The Allegheny Front is the major southeast or east facing escarpment in the Allegheny Mountains in southern Pennsylvania, western Maryland, eastern West Virginia, and western Virginia. The Allegheny Front forms the boundary between the Ridge and Valley Appalachians to its east and the Appalachian Plateau (locally called the Allegheny Plateau) to its west. The Front is closely associated with the Appalachian Mountains' Eastern Continental Divide, which in this area divides the waters of the Ohio/Mississippi river system, flowing to the Gulf of Mexico, from rivers flowing into Chesapeake Bay and from there into the Atlantic Ocean. The Allegheny Front and the Eastern Continental Divide do not always coincide; for example, the North Branch of the Potomac River begins well west of the Front, at the Fairfax Stone near the southwestern tip of Maryland, about 10 mile (16 km) and across the actual divide from the headwaters of the Youghiogheny River draining northwards into the Monongahela and Ohio rivers. The Allegheny Front is one of the windiest spots east of the Mississippi, leading to the recent establishment of wind farming there.

The Allegheny Front forms part of the Appalachian Structural Front, separating the Appalachian Plateau from the Appalachians' Ridge and Valley Province. The various other escarpments along this structural feature include the Catskill Escarpment to the northeast and the Cumberland Escarpment to the southwest. Other high points along the front include the Dolly Sods Wilderness in West Virginia, a broad, rocky plateau at an elevation of about 4000 feet (1219 m); Dan's Rock on Dans Mountain in Maryland at 2895 feet (882 m); and Blue Knob in northern Bedford County, Pennsylvania, with an elevation greater than 3120 feet (951 m).

Local segments of the Eastern Continental Divide usually pass within a few miles of the Allegheny Front and in many places coincide with it; this divide between waters of the Atlantic Ocean and the Gulf of Mexico separates the westward flowing Ohio River watershed from the eastward flowing watersheds of the Susquehanna, Potomac, and James rivers. Numerous eastward flowing streams have their headwaters incised into Allegheny Front, displacing the divide westward from the front, including the North Branch of the Potomac River west of Cumberland, Maryland, which originates well into the Appalachian Plateau at the Fairfax Stone, just south of Maryland's southwestern tip. No waterway crosses the front from east to west.

The Allegheny Front begins in central Pennsylvania northwest of Lock Haven and extends southwest paralleling Bald Eagle Mountain and Brush Mountain to its east. The front continues to a point north of the Pennsylvania/Maryland boundary where it is offset about 10 mile (16 km) to the east as it changes from the bold escarpment that characterized it west of Altoona to its more gentle rise in Maryland. Across the Mason–Dixon line in Maryland, the front becomes Dans Mountain, west of Cumberland, which reaches 2895 feet (882 m) at Dan's Rock. Along Maryland's southern border, the North Branch of the Potomac River cuts down through the front at 790 feet (241 m) just west of Keyser, West Virginia. South of the Potomac in West Virginia, the front continues through the Mount Storm area, then passes along the eastern edge of Dolly Sods, a wide plateau of Pottsville conglomerate bedrock at about 4000 feet (1219 m) elevation. From the Sods, the front continues southward as an increasingly steep escarpment west of the North Fork of the South Branch Potomac River, with the Roaring Plains West Wilderness continuing the high plateaus of the Dolly Sods area along the escarpment's crest. The Allegheny Front's southern end is Mount Porte Crayon (4770 feet (1454 m)), after which the land drops steeply to Seneca Creek, west of Seneca Rocks.

In the Dolly Sods Wilderness of West Virginia, and southward toward Mount Porte Crayon, the front is topped for more than 10 mile (16 km) by a broad, nearly flat plateau with many wide areas of exposed bedrock along the edge of the escarpment's drop to the North Fork River to the east, along the front's base. Many of these windswept cliff edge outcrops are sparsely vegetated, with occasional one sided (flagged) red spruce (Picea rubens) trees, and open habitats dominated by various low growing Appalachian and boreal plant species.

The long, steep, nearly continuous, often windswept escarpment of the Allegheny Front has both positive and negative effects on society and culture in the central Appalachians region.

Few roads or railroads cross the Allegheny Front, limiting transportation and communication between the regions to its east and west. Establishing passage of the front was key to the development of the U. S. railroad network during the second half of the 19th century, thereby connecting the Midwest by rail with the Atlantic seaboard. The Pennsylvania Railroad built the Horseshoe Curve track section west of Altoona, so that freight trains could ascend or descend to or from the Allegheny Plateau to the west.

Substantial portions of the Allegheny Front's crest and slopes are parts of a national forest (the Monongahela in West Virginia) or various state, local, or private wildlands parks or preserves. The few readily accessible scenic viewpoints atop the Allegheny Front are popular tourist destinations. The Skyline Overlook along U. S. Route 50 in West Virginia is readily accessible by a major road. The front is also a significant part of scenic views from various highways and mountains to its east, such as North Fork Mountain in West Virginia.

The NedPower Mount Storm Wind Project in West Virginia includes 132 wind turbines along 12 mile (19 km) of the Allegheny Front in Grant County near Mount Storm. Constructed between 2006 and 2008, it generates up to 264 megawatts of electricity for the mid Atlantic power grid, enough to service about 66,000 homes and businesses. In December 2016, Save Our Allegheny Ridges, a group that opposes energy development on forested mountaintops, said in a news release that Invenergy plans to install a series of wind turbines atop Shaffer Mountain in Somerset County just a few miles north of the Allegheny Front Hawk Watch.