The Pittsburgh Line is the Norfolk Southern Railway's primary east–west artery in its Pittsburgh Division and Harrisburg Division across the state of Pennsylvania. Formerly the Pennsylvania Railroad's (PRR) Middle Division main line, the Pittsburgh Line spans between the state capitol in Harrisburg and its namesake city of Pittsburgh, crossing the Allegheny Mountains through the Gallitzin Tunnels west of Altoona and the famous Horseshoe Curve in the process. Its east end is marked with the railroad's Harrisburg Line to Reading and Philadelphia, and the Fort Wayne Line on its west end to Conway, Pennsylvania and points west in Ohio and Indiana. The Pittsburgh Line is arguably Norfolk Southern's busiest freight corridor, where 50 to 70 trains traverse the line daily.