The Joralemon Street Tunnel opened in January 1908 between Lower Manhattan and a temporary terminus at Borough Hall, the first underground subway station in Brooklyn. The line was to extend three more stops to Atlantic Avenue; this extension was nearly complete by March, except for the Atlantic Avenue station. The extension opened on May 1, 1908; the first train, an express from Manhattan, left Bowling Green at 1:02 a.m. and entered Atlantic Avenue sixteen minutes later. The stations' opening was marked with a parade and a poem praising Belmont. According to The New York Times, the extension was "regarded as of the utmost importance" because it connected the IRT with the LIRR for the first time. The extension relieved congestion at the overcrowded Borough Hall station; trains from Atlantic Avenue were already crowded by the time they reached Borough Hall.
