 The line runs from Philadelphia, where it meets the Northeast Corridor at Zoo interlocking (milepost 1.9), west to Harrisburg (MP 104.6), where electrification ends.It is part of the longer Keystone Corridor, which continues west to Pittsburgh along the Norfolk Southern Railway's Pittsburgh Line.This section is sometimes referred to as "Keystone East" and is part of Amtrak's Keystone Service.