Horseshoe Curve National Historic Landmark

Horseshoe Curve is a three-track railroad curve on Norfolk Southern Railway's Pittsburgh Line in Blair County, Pennsylvania. The curve is about 2,375 feet long and 1,300 feet 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: 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 was added to the National Register of Historic Places and designated a National Historic Landmark in 1966. It became a National Historic Civil Engineering Landmark in 2004.