Conrail & CSX
By the consolidation of Erie Lackawanna and Penn Central (among others) into Conrail in 1976, both the West Shore Railroad and the Northern Branch fell under the control of Conrail. As trains accessing the Northern Branch in Jersey City had to go to Journal Square and reverse direction, and the connection included a grade crossing of Newark Avenue, freight trains typically used the New Jersey Junction Railroad and West Shore Railroad, renamed as Conrail's River Line, to go through northern New Jersey.
Around 1994, a short elevated track, known as the Marion Running Track, was built to connect the Passaic and Harsimus Line towards Kearny with the Northern Branch. This provided the Northern Branch with a direct connection to other lines heading west and south at Marion Junction.
After the breakup of Conrail in 1999, the Northern Branch was divided. Conrail Shared Assets Operations retained the tracks from Marion Junction to the CSX yard in North Bergen, known as the Northern Running Track. CSX was given the remaining section north to Northvale, in addition to the West Shore Railroad running through the yard, known as the Bergen Subdivision of the River Line.
With New Jersey Transit's 2000 creation of the Hudson–Bergen Light Rail on the River Line east of the CSX North Bergen Yard, freight trains needed an alternate route to get to the CSX Albany Division. Trains were re-routed via the Northern Running Track to access the Bergen Subdivision and this part of the Northern Branch became major CSX rail corridor from Upstate New York. At that time, the Northern Running Track was improved to handle the heavier traffic that had formerly used the River Line on the east side of the New Jersey Palisades. New Jersey Transit paid for the project, which included double-tracking the line, changing Marion Junction and Bergen Junction, and building overpasses on Secaucus Road and Paterson Plank Road. The rest of the Northern Branch continues north to the New York state line, and is a minor spur.