Horseshoe Curve (Pennsylvania)

The Horseshoe Curve is a three-track railroad curve on Norfolk Southern Railway's Pittsburgh Line in Blair County, Pennsylvania. The curve is roughly 2,375 feet (700 m) long and 1,300 feet (400 m) in diameter. Completed in 1854 by the Pennsylvania Railroad as a way to reduce the westbound grade to the summit of the Allegheny Mountains, it replaced the time-consuming Allegheny Portage Railroad, which was the only other route across the mountains for large vehicles. The curve was later owned and used by three Pennsylvania Railroad successors: Penn Central, Conrail, and Norfolk Southern.

Horseshoe Curve has long been a tourist attraction. A trackside observation park was completed in 1879. The park was renovated and a visitor center built in the early 1990s. The Railroaders Memorial Museum in Altoona manages the center, which has exhibits pertaining to the curve. The Horseshoe Curve was added to the National Register of Historic Places and designated as a National Historic Landmark in 1966. It became a National Historic Civil Engineering Landmark in 2004.