Blair Gap, one of the gaps of the Allegheny, is a water gap along the eastern face atop the Allegheny Ridge or Allegheny Front escarpment. Like other gaps of the Allegheny, the slopes of Blair Gap were amenable to foot travel, pack mules, and possibly wagons, allowing Native Americans, and then, after about 1778–1780 settlers, to travel west into the relatively un-populated 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, which as was authorized by the enabling acts in 1824 of Pennsylvania's Main Line of Public Works as part of the Pennsylvania Canal System which originally envisioned linking Pittsburgh to Philadelphia by canals.
