Ryogoku Station is a station in Tokyo's Sumida ward at the east end of the metropolis, and serves the JR Sobu line. Ryogoku Station dates from 1904 when the then private Sobu Line was first established here.
The Sobu Railway line began in 1894 with the establishment of a line from Sakura, about 40 km east of Ryogoku, to Ichikawa, about 11 km east of Ryogoku. The line was extended as far as Ryogoku in 1904. The construction involved extending the line from what was then Honjo (now Kinshicho) station. That 1.5 km section was the first ever elevated railroad to be built in Japan. It begun as a single-track line, but with provision for double tracks, and was made double-track two years later.
Ryogoku Station is right beside the Sumida River, and Sobu Railway lacked the means to build a bridge, so Ryogoku became the line's Tokyo-side terminal, and the company headquarters was built alongside Ryogoku Station. It so happened that in the same year, 1904, the Tobu Railway line's westernmost station, Azumabashi Station (now the Tokyo Skytree Station) was built. This prompted the construction of the Kameido Line running south from Azumabashi (now Asakusa Station), connecting Azumabashi and Ryogoku. This lasted until 1910, making Ryogoku the terminal station for both the Sobu and the Tobu lines during that time. As such, it was the biggest earning station east of Tokyo, and the sixth-biggest earning station of all Tokyo stations, until 1932 when the line was extended west to Ochanomizu.
Ryogoku Station burnt down in the 1923 Kanto earthquake, and was rebuilt in its present form in 1929.
East of Ryogoku, railway lines were not yet electrified, so the establishment in 1958 of a (steam) express train service between Ryogoku and the Boso Peninsula down south in Chiba prefecture saw Ryogoku somewhat restored to its former glory as a terminal. As Japan's economy grew during this period, so did the numbers of people going down to Boso and back for a day at the beach. Even after electrification, many express trains ended here instead of Shinjuku Station, but this finally ended in 1988.
In 1972, an underground express line between Tokyo Station and Kinshicho Station wsa built as part of the Sobu Line (Rapid), which trains passed Ryogoku by.
So since 1988, Ryogoku Station has served as a local station only.
Ryogoku Station is saved, however, from obscurity by its prominent place as rail hub for Japan's preeminent sumo wrestling area. The Kokugikan sumo stadium is less than five minutes' walk from Ryogoku Station. Ryogoku Station itself features sumo-related paraphernalia inside, and is surrounded by restaurants specializing in the dish associated with sumo wrestling: chanko nabe.
(Most of the information here was provided by the Japanese Wikipedia article on Ryogoku Station.)
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