The Toei Asakusa Line, operated by the Tokyo Metropolitan Bureau of Transportation, sits at the centre of one of Tokyo's most extensive through-running networks and holds a unique place in Japanese rail history. When its first section opened on 4 December 1960 it simultaneously began through-running with Keisei Electric Railway, making it the first subway line in Japan to offer through services with a suburban private railway. The network expanded southward on 21 June 1968 when the line reached Sengakuji and through-running with Keikyū Corporation began, connecting the chain toward Kanagawa Prefecture and ultimately to Haneda Airport via the Keikyu Airport Line. Hokuso Railway joined on 31 March 1991, extending trains into Chiba, and Shibayama Railway was added on 27 October 2002. The opening of the Keisei Narita Sky Access Line on 17 July 2010 gave the network a second high-speed airport corridor, completing its distinction as the only rail network offering direct connections between both of Tokyo's main international airports — Haneda in the southwest and Narita in the northeast.
Service pattern
Through trains run across all operator boundaries during daytime hours. Trains serving both airport access corridors — the Keikyu Airport Line toward Haneda and the Keisei Narita Sky Access Line via Hokuso toward Narita — share the core Toei Asakusa Line trunk between Sengakuji and Oshiage.
Timeline
1960On 4 December 1960 the Toei Asakusa Line opened its first section (Oshiage–Asakusabashi) and simultaneously began through-running with Keisei Electric Railway — the first time in Japan that a subway line offered through services with a suburban private railway.
1968On 21 June 1968 the line extended to Sengakuji, and through-running with Keikyū Corporation began, connecting the network southward toward Kanagawa.
1991On 31 March 1991 through-running with Hokuso Railway began, extending the network's northeastern reach into Chiba.
2002On 27 October 2002 Shibayama Railway joined the network, adding the terminal Shibayama-Chiyoda station.
2010On 17 July 2010 the Keisei Narita Sky Access Line opened, adding a high-speed Narita Airport connection to the network via the Hokuso Line corridor.
