The IRT Second Avenue Line, also known as the Second Avenue El, was an elevated railway in Manhattan, New York City, United States, from 1875 to 1942. It was operated by the Interborough Rapid Transit Company until 1940, when the city took over the bankrupt IRT. Service north of the 57th Street ended on June 11, 1940; the rest of the line closed on June 13, 1942.
In 1875, the Rapid Transit Commission granted the Gilbert Elevated Railway Company the right to construct the railway from Battery Park to the Harlem River along Second Avenue.
The commission also granted the Gilbert Elevated Railway Company the right to operate the Sixth Avenue Elevated and soon afterward the Gilbert Elevated Railway changed its name to the Metropolitan Elevated Railway.
Around 1900, the line was electrified. Between 1914 and 1916 construction was undertaken to install a third track to provide express service on the line during peak hours. Express service commenced on January 17, 1916.
The Second Avenue El did not run entirely on Second Avenue. Its southern terminus was City Hall, and it continued to Chatham Square, where it junctioned with the Third Avenue El and ran east along Division Street and then north to Allen Street. At Houston Street it ran north on First Avenue, where it turned left on 23rd Street ran north on Second Avenue to 129th Street. At that point it joined with the Third Avenue El and crossed the Harlem River into the Bronx.