Keikyū Kurihama Line

The line was opened during the Second World War by the Tokyo Express Electric Railway — the wartime conglomerate known as "Greater Tokyu" into which Keikyu had been merged — as part of its Shōnan Line. The first section, from Yokosuka-Horiuchi (the present Horinouchi) to a provisional Kurihama terminus, opened on 1 December 1942. A short extension from the provisional terminus to Kurihama (the present Keikyū Kurihama) followed on 21 September 1943, and in 1944 that station was renamed Shōnan-Kurihama.

The post-war years brought a string of changes. On 1 February 1948 two intermediate stations were renamed — Narukami to Shin-ōtsu and Shōnan to Shōnan-Ida — and on 1 June 1948 the Keihin Electric Express Railway was separated out of Greater Tokyu as an independent company once more. Capacity was then steadily improved: the Yokosuka-Horiuchi–Shōnan-Ida section was double-tracked on 15 June 1954, centralised traffic control was introduced ten days later, and the Shōnan-Ida–Shōnan-Kurihama section was double-tracked on 15 March 1959. In 1961 the starting station was renamed Horinouchi.

From the early 1960s the line was pushed deeper into the Miura Peninsula in stages. On 1 November 1963 it was extended from Keihin-Kurihama to Nobi (today YRP Nobi), the Keikyu rolling-stock works at Kurihama opening at the same time; on the same day Shōnan-Ida was renamed Kitakurihama and Shōnan-Kurihama became Keihin-Kurihama. The line then reached Tsukuihama on 27 March 1966 and Miurakaigan on 7 July 1966, the Tsukuihama–Miurakaigan section being double-tracked from the outset.

The Kurihama Line increasingly became part of a wider through-running network. Direct limited express services linking Miurakaigan with Keisei Narita began on 31 December 1969, tying the Miura coast to the Keisei network across Tokyo, and automatic train stop (ATS) signalling was introduced across all Keikyu lines on 12 November 1970. The final extension, from Miurakaigan to the present terminus at Misakiguchi, opened on 26 April 1975, completing the line at its current length, and the Keihin-Nagasawa–Tsukuihama section was double-tracked on 27 June 1980.

A wave of renamings in the late 1980s gave the line much of its present character: on 1 June 1987 Keihin-Kurihama was renamed Keikyū Kurihama and Keihin-Nagasawa became Keikyū Nagasawa. Inter-company through services then expanded further — Keisei trains began running onto the line on 19 March 1991 and Toei Asakusa Line trains from 1 April 1993 — and on 1 April 1998 Nobi was renamed YRP Nobi after the nearby Yokosuka Research Park.

In more recent years the line has seen successive signalling and service upgrades. Its safety system was updated to C-ATS on 14 February 2009, and from 7 July 2015 digital space-wave train radio came into use. Limited-stop "Morning Wing" commuter services from Miurakaigan to Shinagawa and Sengakuji were introduced from 7 December 2015, and the daytime timetable on the Keikyū Kurihama–Misakiguchi section was reworked in October 2021 and again in November 2022, reflecting the line's continuing role as the commuter and leisure gateway to the Miura Peninsula.

• 19421 December: the Tokyo Express Electric Railway ('Greater Tokyu') opens the first section, Yokosuka-Horiuchi (now Horinouchi)–provisional Kurihama, as part of its Shōnan Line.
• 194321 September: the section from provisional Kurihama to Kurihama (now Keikyū Kurihama) opens.
• 19481 June: the Keihin Electric Express Railway (Keikyu) is separated out of Greater Tokyu as an independent company (intermediate stations Narukami and Shōnan had been renamed Shin-ōtsu and Shōnan-Ida on 1 February).
• 195415 June: the Yokosuka-Horiuchi–Shōnan-Ida section is double-tracked; centralised traffic control (CTC) follows on 25 June.
• 195915 March: the Shōnan-Ida–Shōnan-Kurihama section is double-tracked.
• 19611 September: the starting station Yokosuka-Horiuchi is renamed Horinouchi.
• 19631 November: the line is extended from Keihin-Kurihama to Nobi (now YRP Nobi), the Keikyu works at Kurihama opening at the same time; Shōnan-Ida is renamed Kitakurihama and Shōnan-Kurihama becomes Keihin-Kurihama.
• 196627 March: extension from Nobi to Tsukuihama opens; on 7 July the line reaches Miurakaigan, the Tsukuihama–Miurakaigan section being double-tracked from the start.
• 196931 December: direct limited express services between Miurakaigan and Keisei Narita begin.
• 197012 November: automatic train stop (ATS) signalling is introduced across all Keikyu lines.
• 197526 April: the final section, Miurakaigan–Misakiguchi, opens, completing the line at its present 13.4 km.
• 198027 June: the Keihin-Nagasawa (now Keikyū Nagasawa)–Tsukuihama section is double-tracked.
• 19871 June: Keihin-Kurihama is renamed Keikyū Kurihama and Keihin-Nagasawa becomes Keikyū Nagasawa.
• 199119 March: Keisei trains begin through-running onto the line; Toei Asakusa Line trains follow on 1 April 1993.
• 19981 April: Nobi is renamed YRP Nobi after the nearby Yokosuka Research Park.
• 20157 July: digital space-wave train radio comes into use; limited-stop 'Morning Wing' commuter services from Miurakaigan to Shinagawa and Sengakuji are introduced from 7 December.