It heads southwest along a private right-of-way, eventually joining an elevated structure above Palmetto Street in Ridgewood and Myrtle Avenue in the Brooklyn neighborhood of Bushwick.

The connection to the Brooklyn Bridge tracks opened on June 18, 1898, along a private right-of-way halfway between Concord Street and Cathedral Place.

In Fiscal Year 1930, the platforms at Seneca Avenue were lengthened to accommodate an eight-car train of Standard subway cars.

[13] The rest of the line from Broadway to Jay Street closed on October 4, 1969, and was demolished soon afterward, ending the MJ service.

[15] In 1986, the New York City Transit Authority launched a study to determine whether to close 79 stations on 11 routes, including the remaining portion of the Myrtle Avenue Line, due to low ridership and high repair costs.

[16][17] Numerous figures, including New York City Council member Carol Greitzer, criticized the plans.

[17][18] In July 2017, the Metropolitan Transportation Authority started rebuilding two parts of the Myrtle Avenue Line, the 310-foot-long (94 m) approaches to the junction with the BMT Jamaica Line (which lasted until April 2018, requiring suspension of service between Wyckoff and Myrtle Avenues), and the Fresh Pond Bridge over the Montauk Branch in Queens (which lasted from July to September 2017).