Yotsubashi Line

The line is the third-oldest of the Osaka subway, after the Midōsuji Line and the section that became the Tanimachi Line. Its first stretch, a single-track segment between Daikokuchō and Hanazonochō, opened on 10 May 1942, in the early years of the Pacific War. At first it was operated as a single-track shuttle worked by single cars, and it was conceived as the southern part of a planned No. 3 route that would eventually run up the western side of the city. Wartime and immediate postwar conditions delayed any further extension, and the short line stood largely on its own for more than a decade.

The segment was double-tracked on 3 April 1948, and the line was then lengthened southward in stages: from Hanazonochō to Kishinosato on 1 June 1956 (1.1 km) and from Kishinosato to Tamade on 31 May 1958 (1.3 km). Two-car operation began on 1 September 1959. These extensions gradually built up the southern half of the route through the older residential and industrial districts west of the Midōsuji corridor.

The line's character changed decisively on 1 October 1965, when the long northern extension from Daikokuchō to Nishi-Umeda (4.9 km) opened, carrying the line into the Umeda commercial district and giving it a northern terminus beside the Midōsuji Line's Umeda station. Four-car operation began on the same day. The new section ran beneath Yotsubashi-suji, the street from which the line takes its name, and turned what had been a modest southern shuttle into a through artery serving the western side of the city centre. The route name "Yotsubashi Line" was formally adopted on 6 December 1969.

The line reached its present extent on 9 November 1972, when the final segment from Tamade to Suminoekōen (2.8 km) opened, completing the route from Nishi-Umeda to Suminoekōen. Five-car operation began with this extension, automatic train control and centralised traffic control were introduced, and the Midorigichō depot was opened to serve the line. From this point the Yotsubashi Line ran its full 11.4-kilometre length with 11 stations, the configuration it retains today.

Through the later twentieth century the line lengthened its trains and renewed its rolling stock. The 23 series cars were introduced from 1 June 1990, gradually replacing the earlier 30 series stainless-steel cars, which were withdrawn in November 1996. Six-car operation began on 26 October 1996 and was extended to all trains by 29 March 1997. For most of its history the line was run by the Osaka Municipal Transportation Bureau, but on 1 April 2018 the Osaka municipal subway was corporatised and the Yotsubashi Line, along with the rest of the network, passed to the newly formed Osaka Metro Co., Ltd. (大阪市高速電気軌道); the change of operator was seamless to passengers.

Today the Yotsubashi Line is one of Osaka Metro's core north-south routes, running parallel to and west of the Midōsuji Line and sharing several of its busiest interchange districts — Umeda, Hommachi and Namba — while serving the western parts of the city centre and the residential districts of southern Osaka. Worked by 23 series trains in six-car formations, it continues to function as a relief route for the heavily used Midōsuji Line and a direct link between the Umeda terminal area and the Suminoe district in the south.

• 194210 May: the line opens as a single-track segment between Daikokuchō and Hanazonochō (1.3 km), worked by single cars.
• 19483 April: the Daikokuchō–Hanazonochō segment is double-tracked.
• 19561 June: the line is extended from Hanazonochō to Kishinosato (1.1 km).
• 195831 May: the line is extended from Kishinosato to Tamade (1.3 km).
• 19591 September: two-car operation begins.
• 19651 October: the northern extension from Daikokuchō to Nishi-Umeda (4.9 km) opens, carrying the line into the Umeda district; four-car operation begins.
• 19696 December: the route is formally given the name 'Yotsubashi Line'.
• 19729 November: the final segment from Tamade to Suminoekōen (2.8 km) opens, completing the line end to end; five-car operation begins and ATC/CTC are introduced, with the Midorigichō depot opened.
• 19901 June: the 23 series cars are introduced, gradually replacing the earlier 30 series stainless-steel cars.
• 199626 October: six-car operation begins; the 30 series stainless-steel cars are withdrawn in November.
• 199729 March: all trains are converted to six-car formations.
• 20181 April: the Osaka municipal subway is corporatised; the Yotsubashi Line passes to the newly formed Osaka Metro Co., Ltd. (大阪市高速電気軌道).