Keiō Line
Shinjuku Station opened in 1885 as a stop on Japan Railway's Akabane-Shinagawa line (now part of the Yamanote Line). Shinjuku was still a quiet community at the time and the station was not heavily trafficked at first. The opening of the Chūō Line (1889), Keiō Line (1915) and Odakyū Line (1923) led to increasing traffic through the station.