The IRT Jerome Avenue Line, also unofficially known as IRT Woodlawn Line, is a New York City Subway Line along Jerome Avenue in the Bronx. It was opened on June 2, 1917 as a shuttle service between Kingsbridge Road and 149th Street. This was in advance of through service to the IRT Lexington Avenue Line, which began on July 17, 1918. The line was extended from Kingsbridge Road to Woodlawn on April 15, 1918.
In 1918, the Ninth Avenue elevated was extended from the Polo Grounds terminal, entering the Bronx via the Putnam Bridge, a now-demolished swing bridge immediately north of the Macombs Dam Bridge, to connect with the Jerome Avenue line between 161st Street and 167th Street. After the lower portion of the Ninth Avenue Line closed on June 12, 1940, a shuttle continued to operate to the Polo Grounds until after the New York Giants moved to San Francisco. The shuttle closed on August 31, 1958.
The Jerome Avenue Line is served locally by the 4 train at all times, except for the 138th Street – Grand Concourse station, which the 4 serves all times except rush hours in the peak direction, and the 5 at all times except late nights.
As part of a pilot program to evaluate express service on the line, from June 8, 2009 to June 26, 2009, the MTA operated four trains southbound on the express track between 7:15 AM and 8:00 AM. The trains stopped at Woodlawn, Mosholu Parkway, Burnside Avenue, and 149th Street – Grand Concourse, then continued down the normal route. From October 26, 2009, to December 11, 2009, another pilot program to run express service ran, this time adding Bedford Park Boulevard – Lehman College as an additional stop. A fifth train had also been added and trains now run every 20 minutes from 7:00am to 8:20am.