Blair Gap, one of the

gaps of the Allegheny The gaps of the Allegheny, meaning gaps in the Allegheny Ridge (now given the technical name Allegheny Front) in west-central Pennsylvania, is a series of escarpment eroding water gaps (notches or small valleys) along the saddle between two ...

is a

water gap A water gap is a gap that flowing water has carved through a mountain range or mountain ridge and that still carries water today. Such gaps that no longer carry water currents are called wind gaps. Water gaps and wind gaps often offer a prac ...

along the eastern face atop the

Allegheny Ridge 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, USA. The Allegheny Front forms the boundary between the Rid ...

or Allegheny Front

escarpment An escarpment is a steep slope or long cliff that forms as a result of faulting or erosion and separates two relatively level areas having different elevations. The terms ''scarp'' and ''scarp face'' are often used interchangeably with ''escar ...

. Like other'' 'gaps of the Allegheny' ''the slopes of Blair Gap were amenable to foot travel, pack mules, and possibly wagons allowing Amerindians, and then, after about 1778-1780 settlers, to travel west into the relatively depopulated Ohio Country decades before the railroads were born and tied the country together with steel. Historically, the gap was used for the upper sections of the

Allegheny Portage Railroad The Allegheny Portage Railroad was the first railroad constructed through the Allegheny Mountains in central Pennsylvania, United States; it operated from 1834 to 1854 as the first transportation infrastructure through the gaps of the Allegheny ...

, which as was authorized by the

enabling act An enabling act is a piece of legislation by which a legislative body grants an entity which depends on it (for authorization or legitimacy) the power to take certain actions. For example, enabling acts often establish government agencies to car ...

s in 1824 of Pennsylvania's

Main Line of Public Works The Main Line of Public Works was a package of legislation passed by the Commonwealth of Pennsylvania in 1826 to establish a means of transporting freight between Philadelphia and Pittsburgh. It funded the construction of various long-proposed can ...

as part of the

Pennsylvania Canal System The Pennsylvania Canal (or sometimes Pennsylvania Canal system) was a complex system of transportation infrastructure improvements including canals, dams, locks, tow paths, aqueducts, and viaducts. The Canal and Works were constructed and assemb ...

which originally envisioned linking

Pittsburgh Pittsburgh ( ) is a city in the Commonwealth (U.S. state), Commonwealth of Pennsylvania, United States, and the county seat of Allegheny County, Pennsylvania, Allegheny County. It is the most populous city in both Allegheny County and Wester ...

Philadelphia Philadelphia, often called Philly, is the largest city in the Commonwealth of Pennsylvania, the sixth-largest city in the U.S., the second-largest city in both the Northeast megalopolis and Mid-Atlantic regions after New York City. Sinc ...

canal Canals or artificial waterways are waterways or engineered channels built for drainage management (e.g. flood control and irrigation) or for conveyancing water transport vehicles (e.g. water taxi). They carry free, calm surface flow un ...

s. In the early 1900s,

US Route 22 U.S. Route 22 (US 22) is a west–east route and is one of the original United States highways of 1926, running from Cincinnati, Ohio, at US 27, US 42, US 127, and US 52 to Newark, New Jersey, at U.S. Route 1/9 in the Newark Airport Interchange ...

followed alongside the watercourse through the gap. Until around the 1920s, after new founded auto clubs gathered enough numbers to political clout to push for initiatives creating roads between towns, off the railroads the primary means of travel town to town was on foot or where hauling was needed, using wagons. There were only ''five ways through the Appalachians east to west:'' Around the bottom (plains or Piedmont area) in Georgia, the

Cumberland Gap The Cumberland Gap is a pass through the long ridge of the Cumberland Mountains, within the Appalachian Mountains, near the junction of the U.S. states of Kentucky, Virginia, and Tennessee. It is famous in American colonial history for its rol ...

, the

Cumberland Narrows The Cumberland Narrows (or simply The Narrows) is a water gap in western Maryland in the United States, just west of Cumberland. Wills Creek cuts through the central ridge of the Wills Mountain Anticline at a low elevation here between Wills Mou ...

, the

Front, and up the

Hudson River The Hudson River is a river that flows from north to south primarily through eastern New York. It originates in the Adirondack Mountains of Upstate New York and flows southward through the Hudson Valley to the New York Harbor between N ...

then around the north end of the

Catskills The Catskill Mountains, also known as the Catskills, are a physiographic province of the larger Appalachian Mountains, located in southeastern New York. As a cultural and geographic region, the Catskills are generally defined as those areas cl ...

and across upstate New York, the so-called level water route to the

Great Lakes The Great Lakes, also called the Great Lakes of North America, are a series of large interconnected freshwater lakes in the mid-east region of North America that connect to the Atlantic Ocean via the Saint Lawrence River. There are five lakes ...

. All other transits involve difficult climbs a man on foot can only make with great difficulty, and which animal drawn transport could not. Geographically and geologically, without the large projects and engineering capabilities of the 20th century, there were exactly three internal regions where it was possible to get animal powered vehicles from the east side to the west side of the Appalachian Mountains, making five routes overall counting traveling around the plains at either end of the western chain. Below

Canada Canada is a country in North America. Its ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, covering over , making it the world's second-largest country by tot ...

, the geologic nature of successive

barrier ridge The terms barrier ridge, a term of art in the earth sciences, especially geology and sometimes barrier range (more common as a geography term) describing the existence of gross landforms describing long ridgelines which are particularly difficult ...

s of the

Ridge and Valley Appalachians The Ridge-and-Valley Appalachians, also called the Ridge and Valley Province or the Valley and Ridge Appalachians, are a physiographic province of the larger Appalachian division and are also a belt within the Appalachian Mountains extending ...

runs from the valley of the Hudson, the

Delaware Water Gap Delaware Water Gap is a water gap on the border of the U.S. states of New Jersey and Pennsylvania where the Delaware River cuts through a large ridge of the Appalachian Mountains. The gap makes up the southern portion of the Delaware Water Gap N ...

down through all of

northern Pennsylvania The Northern Tier is a geographic region consisting of five rural counties in north-central Pennsylvania. Geography The region is bordered to the north by the Southern Tier of New York state. Together, these regions are known as the Twin Tiers ...

, sundering eastern and central Pennsylvania,

Maryland Maryland ( ) is a state in the Mid-Atlantic region of the United States. It shares borders with Virginia, West Virginia, and the District of Columbia to its south and west; Pennsylvania to its north; and Delaware and the Atlantic Ocean to ...

and

North Carolina North Carolina () is a state in the Southeastern region of the United States. The state is the 28th largest and 9th-most populous of the United States. It is bordered by Virginia to the north, the Atlantic Ocean to the east, Georgia and So ...

Virginia Virginia, officially the Commonwealth of Virginia, is a state in the Mid-Atlantic and Southeastern regions of the United States, between the Atlantic Coast and the Appalachian Mountains. The geography and climate of the Commonwealth ar ...

from the eastern

Western Pennsylvania Western Pennsylvania is a region in the U.S. state of Pennsylvania, covering the western third of the state. Pittsburgh is the region's principal city, with a metropolitan area population of about 2.4 million people, and serves as its economic ...

West Virginia West Virginia is a state in the Appalachian, Mid-Atlantic and Southeastern regions of the United States.The Census Bureau and the Association of American Geographers classify West Virginia as part of the Southern United States while the Bur ...

Kentucky Kentucky ( , ), officially the Commonwealth of Kentucky, is a state in the Southeastern region of the United States and one of the states of the Upper South. It borders Illinois, Indiana, and Ohio to the north; West Virginia and Virginia to ...

, and

Tennessee Tennessee ( , ), officially the State of Tennessee, is a landlocked state in the Southeastern region of the United States. Tennessee is the 36th-largest by area and the 15th-most populous of the 50 states. It is bordered by Kentucky to th ...

Notes

References

{{coord, 40, 27, 25, N, 78, 32, 52, W, region:US-PA_source:GNIS, display=title Landforms of Blair County, Pennsylvania Water gaps of Pennsylvania