Kesennuma Line

The idea of a railway along the Sanriku coast dates to 1896, when the Meiji Sanriku earthquake of that June sent a great tsunami into the region and killed more than twenty thousand people; building a railway was floated as part of the recovery but did not advance. Local campaigning continued for decades, and in 1922 a route "from Kesennuma via Tsuya and Shizugawa to Maeyachi, with a branch from Tsuya via Sanuma to Tajiri" was written into the appended table of the Railway Construction Act. After the Shōwa Sanriku earthquake struck the coast again in March 1933, attention returned to the project, but the listing offered two possible inland routes — one to Maeyachi and one to Tajiri — and inland and coastal towns clashed over which to build. The government finally settled the dispute in favour of the Maeyachi route, judging it the more advantageous for developing the Sanriku coast.

In 1935 the Railway Ministry resolved to begin construction of the line from Kesennuma toward Maeyachi the following year, and work proceeded southward from Kesennuma. Construction was interrupted in 1937 by the outbreak of the Second Sino-Japanese War, resumed in 1939, and suspended once more in 1943 during the Pacific War; work had continued into wartime in part because the line was expected to carry mineral resources from the Ōya mine. After the war, in 1946, towns and villages along the route formed a promotion association and began petitioning for the work to restart, but the immediate priority was rebuilding existing lines. The project was revived as a Class-B construction line with a supplementary budget in 1952, and work resumed in 1953.

A freight branch from Kesennuma to Kesennuma-Kō opened in 1956 ahead of passenger services, and on 11 February 1957 the Kesennuma Line opened in part, running passenger trains between Kesennuma and Motoyoshi; six round trips a day used the new section. The remaining gap to Maeyachi was slow to follow: the construction council approved the work in 1959, a ground-breaking was held at Maeyachi in 1962, and from 1964 the newly created Japan Railway Construction Public Corporation took over building it. While that work was under way, the National Railways' advisory committee in June 1968 proposed closing 83 deficit-ridden lines — the Kesennuma Line among them — alarming the communities along the route. Even so, on 24 October 1968 the Maeyachi–Yanaizu section opened as the separately named Yanaizu Line.

The final stretch between Yanaizu and Motoyoshi crossed the steep ria coastline, where bridges and tunnels made up sixty-four per cent of the route and the Yokoyama Tunnel alone ran 3,508 metres — the longest on the line. After this difficult and costly work, the Kesennuma Line was completed and opened throughout on 11 December 1977; with the National Railways under financial strain and its president unwilling to take on certain money-losing lines, the Yanaizu–Motoyoshi section proved to be the last local line that Japanese National Railways ever opened. The Yanaizu Line was merged back in and the through route from Maeyachi to Kesennuma, 72.8 kilometres long, took the Kesennuma Line name. Although the 1980 reconstruction law set criteria for closing lightly used lines, the Kesennuma Line was exempted because its passengers' average journey was long enough and numerous enough to qualify. The line passed to JR East on 1 April 1987, and one-man operation began across the line on 14 March 1992.

On 11 March 2011 the Tōhoku earthquake and the tsunami that followed left the whole line out of service. The coastal section between Rikuzen-Togura and Minami-Kesennuma was devastated: nine stations — among them Rikuzen-Togura, Shizugawa, Utatsu and Minami-Kesennuma — were swept away, the Tsuyagawa bridge collapsed, and roadbed and embankments were washed out in many places. An up train that had made an emergency stop between Matsuiwa and Saichi was carried off by the wave, though its crew and passengers had already evacuated. The inland Maeyachi–Yanaizu section was repaired and reopened about six weeks later, on 29 April 2011, but JR East said restoring the rest as a railway would take years, and it later abandoned rail rebuilding in the face of relocation costs and falling ridership.

For the severed coastal section JR East proposed conversion to a dedicated bus rapid transit route, which it formally put to local authorities on 27 December 2011. The municipalities of Kesennuma, Minamisanriku and Tome agreed to a BRT "provisional restoration" in May 2012; provisional BRT service between Yanaizu and Kesennuma, run as a bus substitution, began on 20 August 2012, and full-scale BRT operation followed on 22 December 2012, with the former trackbed converted to a dedicated busway. The BRT was extended west to Maeyachi in 2015, and in 2016 the local authorities agreed with JR East that BRT would be the line's permanent form. JR East filed to abolish the Yanaizu–Kesennuma railway in November 2019, and the 55.3-kilometre section, with its sixteen stations, was formally abolished on 1 April 2020. The Kesennuma Line today is a short local railway between Maeyachi and Yanaizu worked by KiHa 110 series diesel cars, paralleled and continued by the BRT, whose Hino Blue Ribbon City buses have run with Level 2 self-driving since December 2022.

• 1922A route from Kesennuma via Tsuya and Shizugawa to Maeyachi (with a branch via Sanuma to Tajiri) is added to the appended table of the Railway Construction Act.
• 1935The Railway Ministry decides to begin building the Kesennuma–Maeyachi line the following year; construction proceeds southward from Kesennuma.
• 1937Construction is interrupted by the outbreak of the Second Sino-Japanese War; it resumes in 1939 and is suspended again in 1943 during the Pacific War.
• 195611 April: a freight branch from Kesennuma to Kesennuma-Kō opens (5.8 km), ahead of passenger services.
• 195711 February: the Kesennuma Line partially opens, with passenger trains running between Kesennuma and Motoyoshi; six round trips a day use the section.
• 196824 October: the Maeyachi–Yanaizu section (17.5 km) opens separately as the Yanaizu Line, months after the National Railways' advisory committee proposed closing 83 deficit lines including this one.
• 197711 December: the Yanaizu–Motoyoshi section (34.0 km) opens, completing the line throughout; the Yanaizu Line is merged in and the 72.8 km Maeyachi–Kesennuma route becomes the Kesennuma Line — the last local line opened by Japanese National Railways.
• 19791 November: the remaining freight branch (Minami-Kesennuma–Kesennuma-Kō) is abolished and Kesennuma-Kō freight station closes.
• 19871 April: with the breakup of Japanese National Railways, the Kesennuma Line is transferred to JR East.
• 199722 March: Ōya Station is renamed Ōyakaigan Station.
• 201111 March: the Tōhoku earthquake and tsunami close the whole line; nine coastal stations are swept away and a stranded up train is carried off (its crew and passengers having evacuated). The inland Maeyachi–Yanaizu section reopens on 29 April.
• 2012BRT is adopted for the severed coastal section: provisional BRT service between Yanaizu and Kesennuma begins on 20 August (run as a bus substitution), and full-scale BRT operation starts on 22 December.
• 201527 June: the BRT is extended westward to Maeyachi Station, running parallel to the surviving railway.
• 20201 April: the Yanaizu–Kesennuma railway (55.3 km, sixteen stations) is formally abolished, having been served by BRT since 2012; only the Maeyachi–Yanaizu railway remains.