The line north of the split at Jenkintown was originally built as the National Railway project, opened on May 1, 1876, to provide an alternate to the United New Jersey Railroad and Canal Companies' monopoly over Philadelphia- New York City travel.
The RDG planned to also electrify tracks between West Trenton and the CNJ Terminal in Jersey City for long-distance service, but had to drop plans for electrification outside of the commuter service area due to economic setbacks as a result of the Great Depression. Electrified service to West Trenton was opened on July 26, 1931. Like all of the Reading Company's commuter lines, the West Trenton Line was electrified in the early 1930s and has a mix of at-grade and grade separated crossings.
See also: New York Branch West Trenton station
