In 1851 J. Edgar Thomson, the first Chief Engineer of the young Pennsylvania Railroad began construction of the Mountain Division between the Johnstown area and Altoona. Thomson faced two significant obstacles on the division, how to tunnel through the solid rock walls near the summit and how to get the Main Line from Altoona west up the mountain.
Thomson's endeavor for the PRR was not the first route over the Alleghenies in Blair County. The Allegheny Portage Railroad, part of the state-owned Main Line of Public Works completed in 1834, utilized a series ten inclined planes, five on either side of the summit, to surmount the Alleghenies. It proved to be a slow and dangerous part of an already arduous journey that required train, canal and these inclined planes to travel across the Commonwealth, taking some 4.5 days.
Thomson opted to by-pass the troubled Main Line of Public Works and the APRR all together, turning west from the Juniata Valley in Altoona. To maintain a route with a ruling grade of 1.8% the new railroad would hug the foothills toward the summit, utilizing the natural topography of the ridge to Kittanning Point. Here, the Kittanning and Glen White Runs converge in the valley of Burgoon Run creating a significant challenge. Faced with a decision of spanning the considerable gap of Burgoon Run, Thomson, instead employed Irish laborers wielding pickaxes and shovels to fill the gaps of Kittanning and Glen White Run and thus completing the arced curve around Burgoon Run that became known as the Horseshoe Curve.
The line over the Alleghenies and Horse Shoe Curve opened on for service on February 15, 1854. Though the State Works attempted to improve their route by opening the New Portage Railroad in 1855, it ultimately failed, later becoming part of the PRR system, serving as an alternative route in times where traffic warranted its use. After 164 years of continual operation Horseshoe Curve continues to be a vital piece of rail transportation infrastructure, a testament to Thomson’s engineering ability in constructing one of the most celebrated railroads in American history.