The Horseshoe Curve is known worldwide as an engineering achievement by the Pennsylvania Railroad. This landmark, located just west of Altoona, opened to traffic on February 15, 1854, and it enabled a railroad line to climb the Allegheny Mountains and the eastern continental divide. The Horseshoe Curveas construction impacted railroad design and development for mountainous terrain everywhere, enabling access to coal and other raw materials essential for the industrial age. J. Edgar Thomson, chief engineer of the Pennsylvania Railroad, is widely recognized for his engineering and design of the Horseshoe Curve, a concept never utilized previously. Today the curve is still in use and sees approximately 70 trains daily. Through vintage photographs, Horseshoe Curve chronicles how this marvel remains one of the vital transportation arteries linking the east and west coasts of the United States.