Ishinomaki Line

The line had two separate private origins. The inland half began with the Senpoku Light Railway (仙北軽便鉄道), which was granted a railway licence on 23 August 1911 and opened a 762 mm narrow-gauge line between Kogota and Ishinomaki on 28 October 1912, establishing stations at Wakuya, Maeyachi, Kakeyama, Kanomata and Ishinomaki. A separate licence for a Tome–Tsukidate branch was cancelled in 1914.

The Kogota–Ishinomaki line was nationalised on 1 April 1919 and named the Senpoku Light Line (仙北軽便線). The state regauged it from 762 mm to the standard 1,067 mm narrow gauge on 23 May 1920. The route was renamed the Ishinomaki Light Line (石巻軽便線) on 1 January 1921 and finally the Ishinomaki Line (石巻線) on 2 September 1922.

The coastal half had its own private predecessor, the Oshika Light Railway (鹿軽便鉄道), which opened a 762 mm horse-drawn tramway from Ishinomaki to Watanoha in 1915 and extended it to Onagawa in 1924, introducing a petrol-driven locomotive in 1926. This line too was nationalised in 1939 and regauged to 1,067 mm the same year; the Ishinomaki–Onagawa section opened as part of the state Ishinomaki Line on 7 October 1939, adding the stations Rikuzen-Inai, Watanoha, Sawada and Onagawa and completing the through route from Kogota to the coast. Petrol railcars had already begun running on the Kogota–Ishinomaki section in 1934, and diesel railcars entered service from 1953.

The line was expanded and modernised through the post-war decades. A 1.4-kilometre freight branch from Onagawa to Onagawa Port opened on 11 August 1958. Several intermediate stations were added in the 1950s and later — Urashuku (1956), Sobanokami (1956), Kami-Wakuya (1957), Mangokuura (1989) — while steam locomotives (the C11 class) ran until 24 March 1974. The line was administratively moved from the Riku'u group to the Tōhoku group of lines in December 1977; the Onagawa–Onagawa Port freight branch closed on 1 August 1980; and on 1 April 1987 the line passed to JR East in the breakup and privatisation of Japanese National Railways. One-man operation began on 16 March 1991.

The Ishinomaki Line was severely damaged by the Great East Japan Earthquake and tsunami of 11 March 2011, which halted the whole line; the coastal Ishinomaki–Onagawa end was hit especially hard. Recovery was staged from the inland side outward. Kogota–Maeyachi reopened on 17 April 2011 and Maeyachi–Ishinomaki on 19 May 2011, restoring the inland section within about two months. Ishinomaki–Watanoha followed on 17 March 2012, and Watanoha–Urashuku on 16 March 2013. The final coastal stretch, Urashuku–Onagawa, did not reopen until 21 March 2015, four years after the disaster.

Since the recovery the line has been reintegrated into the wider Sendai-area network. The whole line was brought into the new Sendai suburban zone on 1 April 2014, and from 6 August 2016 one round trip of the Senseki-Tōhoku Line began running through onto the Ishinomaki–Onagawa section, giving the rebuilt coastal end of the line a direct link toward Sendai.

• 191123 August: the Senpoku Light Railway is granted a railway licence (Kogota–Ishinomaki, and a Tome–Tsukidate branch).
• 191228 October: the Senpoku Light Railway opens the Kogota–Ishinomaki section at 762 mm gauge, with stations at Wakuya, Maeyachi, Kakeyama, Kanomata and Ishinomaki.
• 1915The Oshika Light Railway opens a 762 mm horse-drawn tramway from Ishinomaki to Watanoha.
• 19191 April: the Kogota–Ishinomaki line is nationalised and named the Senpoku Light Line.
• 192023 May: the Kogota–Ishinomaki section is regauged from 762 mm to 1,067 mm.
• 19222 September: the route is renamed the Ishinomaki Line (having been the Ishinomaki Light Line since 1 January 1921).
• 1924The Oshika Light Railway extends its line from Watanoha to Onagawa.
• 19397 October: the Ishinomaki–Onagawa section opens as part of the state Ishinomaki Line (the former Oshika Light Railway, nationalised and regauged to 1,067 mm that year), adding Rikuzen-Inai, Watanoha, Sawada and Onagawa.
• 195811 August: a 1.4 km freight branch from Onagawa to Onagawa Port opens.
• 197424 March: steam-locomotive operation (the C11 class) ends.
• 19801 August: the Onagawa–Onagawa Port freight branch is closed.
• 19871 April: with the breakup and privatisation of Japanese National Railways, the line passes to JR East.
• 199116 March: one-man (driver-only) operation begins.
• 201111 March: the Great East Japan Earthquake and tsunami halt the entire line; Kogota–Maeyachi reopens 17 April and Maeyachi–Ishinomaki 19 May, restoring the inland section.
• 201217 March: the Ishinomaki–Watanoha section reopens, about a year after the disaster.
• 201316 March: the Watanoha–Urashuku section reopens, about two years after the disaster.
• 201521 March: the final coastal section, Urashuku–Onagawa, reopens, completing the line's post-tsunami recovery four years on.
• 20166 August: one round trip of the Senseki-Tōhoku Line begins running through onto the Ishinomaki–Onagawa section.