The Keio Line (京王線) is a railway line run by Keio Electric Railway (京王電鉄). It runs from Shinjuku Station in Shinjuku Ward, Tokyo, via Chofu and Kitano to Keio-Hachioji Station in Hachioji.
History
Keio Electric Railway (京王電気軌道) opened the first section, from Sasazuka to Chofu, in 1913. It extended the line in small steps and completed the line from Shinjuku Oiwake to Fuchu in 1916. Buses linked the sections that were not yet open, and Japanese Wikipedia says this was the first bus service in Tokyo. The line followed the Koshu Kaido road and linked the old post towns along it. In 1925 a subsidiary, Tamanan Electric Railway (玉南電気鉄道), opened the section from Fuchu to Higashi-Hachioji, now Keio-Hachioji Station. It was built as a railway to qualify for a state subsidy, but Tamanan did not get the subsidy, citing competition with the Chuo Main Line (中央本線). Keio merged Tamanan in 1926 and obtained a tramway licence for the section, changing its track gauge. Through trains from Shinjuku Oiwake to Higashi-Hachioji began on 22 May 1928.
In 1936 the section from Hatagaya to Shinmachi was moved onto a dedicated track built over the Tamagawa Josui waterway, which was covered over. On 31 May 1944 Keio was merged into Tokyu Electric Railway (東京急行電鉄) under the Land Transport Business Adjustment Act, and Tokyu ran the line. On 25 May 1945 the Yamanote air raid damaged Keio Shinjuku Station and the Tenjinbashi substation. The voltage dropped, trains could not climb the bridge slope at the south exit of Shinjuku Station, and service between Keio Shinjuku and Shinmachi stopped. On 24 July 1945 the Shinjuku terminal moved to its present site on the west side, and trains ran into Shinjuku again. On 1 June 1948 Keio Teito Electric Railway (京王帝都電鉄) became independent when the Dai-Tokyu group was broken up.
After World War II the Tama area grew quickly as a commuter area, and use of the Keio Line grew sharply. In 1953 the street-running section beside Shinjuku was moved onto a dedicated track in the middle of the road. The underground Shinjuku Station opened on 1 April 1963, and the voltage was raised to 1500 V in August 1963. Express service began on 1 October 1963. The whole line was made double track on 3 June 1970. In 1971 people began moving into Tama New Town (多摩ニュータウン). In 1974 the Sagamihara Line (相模原線) was extended to Keio Tama Center, and through trains between Shinjuku and Chofu began.
In 1968 a transport council plan for Tokyo Line 10 (東京10号線) was made. It was part of a joint effort to add capacity on the Keio Line, the Keio New Line (京王新線), the Toei Subway Shinjuku Line (都営地下鉄新宿線) and the Sagamihara Line. On 31 October 1978 the Keio New Line opened, and the tracks between Shinjuku and Sasazuka became four. Hatsudai and Hatagaya stations moved to the new line. In return, all Keio Line trains, including local trains, pass through Hatsudai and Hatagaya, which Japanese Wikipedia says made the trains faster. On 16 March 1980 the Toei Subway Shinjuku Line opened and began through running. In July 1983 the up and down tracks between the old Hatsudai area and Sasazuka went underground. On 2 April 1989 Keio-Hachioji Station went underground.
On 28 May 1992 limited express trains began running through to the Sagamihara Line. On 26 December 1992 all Keio Line trains became air-conditioned. On 1 July 1998 the company, then Keio Teito Electric Railway, changed its name to Keio Electric Railway. On 27 March 2001 semi-express service started.
On 11 March 2011 a timetable revision took effect, and the Great East Japan Earthquake (東日本大震災) struck that day. Trains were disrupted all day, and because the power supply was unstable, service stayed reduced after that day. Limited express trains were suspended on 2 July 2011 and resumed on 23 September 2011. On 2 October 2011 the line changed from ground signals to in-cab signalling with Keio ATC.
On 19 August 2012 the section between Shibasaki and Nishi-Chofu went underground. On 22 February 2018 Keio Liner (京王ライナー), a reserved-seat service between Shinjuku, Keio-Hachioji and Hashimoto, started. On 12 March 2022 the limited express and semi-express services were merged into one class called express. In March 2022 the transport ministry extended the approval period for a continuous grade-separation project between Sasazuka and Sengawa to the end of fiscal 2030. On 15 March 2025 the timetable was revised again, with more Keio Liner trains. The latest change Japanese Wikipedia lists is on 16 August 2026, when some trains were moved one minute later.
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Written by an AI from the line's history on Japanese Wikipedia, nothing else, and checked by a program for dates and numbers that are not in those facts. It can still be wrong. Adapted from Japanese Wikipedia, CC BY-SA 4.0; this text is shared under the same licence.