The Gladstone Branch of the Morris & Essex Lines (as their timetable is labeled shared with the Morristown Line) is an entirely electrified rail line running 42 miles from Hoboken Terminal to Gladstone, New Jersey. The line uses the ex-Lackawanna Main Line (shared with the Morristown Line) until Summit, where the branch diverges into a 22 mile single-track branch line with passing sidings at Murray Hill, Stirling, Bernardsville and west of Far Hills. The branch is picturesque going through horse country crossing some intentionally left dirt roads at level-crossings for horseback riders. The line was completed in 1891 by the The Delaware, Lackawanna, and Western Railroad with electrification reaching Gladstone in 1931 using 3,000 Volts DC current. Electrification was changed on August 28, 1984 to more modern 27,500 Volts AC current.

Train service on the line on weekdays consists of hourly off-peak service between Hoboken and Gladstone using Arrow III EMU train cars, trains connect with MidTOWN DIRECT Morristown Line trains for service to and from New York Penn Station. During rush hours more frequent service is provided in the peak direction only due to the single-tracked nature of the branch. Reverse-peak service is not well provided with the earliest arrival into Gladstone at 9:36am (there is one earlier train that arrives and terminates at Bernardsville at 8:31am) and a gap in service leaving Gladstone for Hoboken between 4:43pm and 9:28pm, although there is an 8:15 train originating in Peapack. During rush hour there are also 2 MidTOWN DIRECT trains into Penn Station (one AM MidTOWN direct train originates in Peapack due to yard access, both of these trains skip Secaucus Junction, so except for the Atlantic City line, the Gladstone Branch is the only New Jersey Transit line not to ever serve Secaucus Junction). These MidTOWN DIRECT trains operate as push-pull trainsets using ALP46 electric locomotives and Comet Cars do to the fact that there is a Voltage change at the Kearney connection and the Arrow III cars can’t change voltage on the fly.