Toei Asakusa Line

The line carries the route number "1" (it was historically called Line 1, 1号線) because it was the first Tokyo subway to be planned, in a Tokyo City notification of 1920 that outlined a route from the Shinagawa area through Shimbashi and Kaminarimon to Oshiage. A construction patent granted to early private promoters was revoked after the Great Kantō Earthquake of 1923 because work had not begun. On 1 September 1941, with the establishment of the Teito Rapid Transit Authority, the route licences held by Tokyo City and the private underground-railway companies were transferred to the new authority for a fee. After the war the plan was revised — in 1946 the planned Line 1 ran between Musashi-Koyama and Shimo-Itabashi — and in 1957 the Council for Urban Transport reset it to a Magome-Higashi–Oshiage alignment, with Tokyo and the Teito authority dividing the construction licences.

Construction of the subway's first line began on 27 August 1956, and after years of delay the initial 3.2 km segment between Oshiage and Asakusabashi opened on 4 December 1960 as Toei Line 1. On the same day the line began through-running with Keisei Electric Railway — the first reciprocal through-service in Japan between a subway and a suburban private railway, a landmark in Japanese urban transport. To make through-running possible, the line had been built to the 1,435 mm standard gauge used by Keisei (and later Keikyū) rather than the narrow gauge common elsewhere. Unlike most early plans, the route was also altered to pass through Asakusa to exploit the existing Tobu and Tokyo subway connections there.

The line was then extended in stages through central Tokyo. The Asakusabashi–Higashi-Nihombashi section opened in May 1962 — provisionally as single track after a ground-subsidence accident near Ningyōchō in March 1962 killed one person and delayed the works — followed by Higashi-Nihombashi–Ningyōchō in September 1962, Ningyōchō–Higashi-Ginza in February 1963, and Higashi-Ginza–Shimbashi in December 1963, where the former Shiodome signal station was upgraded to become Shimbashi Station. Shimbashi–Daimon opened in October 1964.

Through-running to the south came in 1968. On 21 June 1968 the Daimon–Sengakuji section opened and reciprocal through-service with Keihin Electric Express Railway (Keikyū) began, giving the line a second private-railway partner. On 15 November 1968 the final Sengakuji–Nishi-Magome section opened, completing the whole line from Nishi-Magome to Oshiage. The line received its first colour — then vermilion — in July 1970, and on 1 July 1978 it was renamed from Toei Line 1 to the Toei Asakusa Line; the formal name was shortened simply to Asakusa Line in April 2000.

The line's airport role grew steadily through the 1990s and 2000s. Edobashi Station was renamed Nihombashi in 1989; through-service with the Hokusō Development Railway (now Hokusō Railway) began on 31 March 1991. When the Keikyū Airport Line reached the provisional Haneda Station (now Tenkūbashi) in 1993, direct trains to Haneda began, and the full opening of the Keikyū Airport Line on 18 November 1998 introduced the Airport Limited Express (Airport Kaitoku) — the subway's first limited-express service. From 1998 the Asakusa Line formed part of a through rail link between Haneda and Narita. Through-service with the Shibayama Railway began on 27 October 2002, and on 17 July 2010 the opening of the Keisei Narita Airport Line (Narita Sky Access) via the Hokusō line added a faster route to Narita Airport.

In recent years the line has been modernised rather than extended. A connecting track to the Toei Ōedo Line, the Shiodome connecting line, opened between Shimbashi and Daimon in 2006, and the C-ATS signalling system was brought into full use across the line by February 2011. From 2014 all trains became eight cars long, the new 5500 series entered service in 2018, and platform-edge doors were progressively installed, with the last station — Oshiage — completed in February 2024, finishing platform-door coverage line-wide.

• 1920Tokyo City Notification No. 2 of 1920 sets out the future Line 1 along a Shinagawa-area–Shimbashi–Kaminarimon–Oshiage route.
• 19411 September: with the establishment of the Teito Rapid Transit Authority, the route licences held by Tokyo City and the private underground-railway companies are transferred to it for a fee.
• 195627 August: construction of the subway's first line begins.
• 19604 December: the first 3.2 km segment, Oshiage–Asakusabashi, opens as Toei Line 1; reciprocal through-service with Keisei Electric Railway begins — Japan's first subway/private-railway through-running.
• 1962A ground-subsidence accident near Ningyōchō in March kills one person; the Asakusabashi–Higashi-Nihombashi section opens in May as provisional single track, with Higashi-Nihombashi–Ningyōchō following in September.
• 1963Ningyōchō–Higashi-Ginza opens in February; Higashi-Ginza–Shimbashi opens in December, the former Shiodome signal station being upgraded to Shimbashi Station.
• 1964October: Shimbashi–Daimon opens (initially single track).
• 196821 June: Daimon–Sengakuji opens and reciprocal through-service with Keihin Electric Express Railway (Keikyū) begins; on 15 November the final Sengakuji–Nishi-Magome section opens, completing the line.
• 1970July: the line's first line colour (then vermilion) is introduced.
• 19781 July: the route is renamed from Toei Line 1 to the Toei Asakusa Line.
• 198919 March: Edobashi Station is renamed Nihombashi.
• 199131 March: reciprocal through-service with the Hokusō Development Railway (now Hokusō Railway) begins.
• 199818 November: with the full opening of the Keikyū Airport Line, the Airport Limited Express (Airport Kaitoku) — the subway's first limited-express service — begins; from this period the line forms part of a Haneda–Narita through rail link.
• 200020 April: the formal name is shortened from Toei Asakusa Line to Asakusa Line.
• 200227 October: reciprocal through-service with the Shibayama Railway begins.
• 201017 July: with the opening of the Keisei Narita Airport Line (Narita Sky Access) via the Hokusō line, through-service to Narita Airport over the new route begins.
• 202420 February: platform-edge doors enter service on all platforms at Oshiage, completing platform-door installation across the whole line.