Ōminato Line

The line opened on 20 March 1921 as the Ōminato Light Railway (大湊軽便線, Ōminato-keibensen), a light line of the government railways, running from Noheji Station to Mutsu-Yokohama Station. It was extended to its present terminus at Ōminato by 25 September 1921, completing the through route down the peninsula. On 2 September 1922 the line was redesignated and renamed simply the Ōminato Line.

Over the following decades the line gained its intermediate stations. Shimokita Station opened on 6 December 1939 as the junction for the Ōhata Line, which opened the same day; Fukkoshi Station followed on 20 March 1943, Arihata on 10 June 1946, Kanayasawa on 10 June 1953, and Kita-Noheji on 20 December 1958. On 1 December 1948 Tanabu Station was renamed Akagawa. Diesel railcars were introduced to the line on 25 February 1960, and on 1 October 1968 the express Natsudomari began running between Aomori and Ōminato.

The line was repeatedly tested by the weather of the Shimokita coast. A concentrated downpour on 23 September 1973 washed out the roadbed and breached embankments at seventy-eight separate points, suspending services; the line did not fully reopen until 13 December, eighty days later. Steam traction ended soon afterwards: the last scheduled steam-locomotive working ran on 11 May 1974, which also marked the disappearance of steam from every railway in Aomori Prefecture. The Natsudomari express was downgraded to a rapid service on 2 October 1978, and was later renamed the Usori and then the Shimokita.

All freight operations on the line ceased on 1 February 1984. With the breakup and privatisation of Japanese National Railways, the East Japan Railway Company succeeded to the line as a Type-1 railway operator on 1 April 1987. One-man operation began on 13 March 1988 (the rapid Natsudomari being renamed the Usori at the same time); KiHa 100 series diesel railcars were introduced from 1 December 1993, when the rapid was renamed the Shimokita. On 8 December 1998 the line's token block working — JR East's last — was abolished in favour of a special automatic block system.

The line's modern isolation dates from the northward march of the Tōhoku Shinkansen. When the Shinkansen reached Hachinohe in 2002, one Shimokita rapid was extended through to Hachinohe Station. Then, on 4 December 2010, the Shinkansen was extended from Hachinohe to Shin-Aomori, and the parallel Hachinohe–Aomori section of the Tōhoku Main Line — including Noheji, the Ōminato Line's junction — was transferred to the third-sector Aoimori Railway. From that day the Ōminato Line, a former branch of the Tōhoku Main Line, was cut off from the rest of the JR East network, reached only over the Aoimori Railway; JR East had announced in November 2007 that it would continue to operate the line as its own after the Shinkansen extension. The day the Shinkansen opened, the hybrid resort train "Resort Asunaro Shimokita" began running using HB-E300 series cars.

Today the Ōminato Line carries local trains calling at every station together with the Shimokita rapid service, both worked by KiHa 100 series diesel railcars based at the Hachinohe depot, which the trains reach via the Aoimori Railway. Tourism has become a significant part of the line's traffic: in addition to the Shimokita rapid, JR East has run a succession of excursion trains over it — the joyful train "Kirakira Michinoku" from 2002, the "Resort Asunaro Shimokita", and later seasonal services such as "Hinabi Shimokita" — drawing visitors to the Shimokita Peninsula. All scheduled trains became one-man-operated from the timetable revision of 13 March 2021.

• 192120 March: the Ōminato Light Railway (大湊軽便線), a government light line, opens between Noheji and Mutsu-Yokohama; Arito and Mutsu-Yokohama stations open.
• 192125 September: the line is extended from Mutsu-Yokohama to Ōminato, completing the route; Chikagawa, Tanabu and Ōminato stations open.
• 19222 September: the line is renamed the Ōminato Line.
• 19396 December: Shimokita Station opens as the junction for the Ōhata Line, which opens the same day.
• 19481 December: Tanabu Station is renamed Akagawa.
• 19681 October: the express Natsudomari begins running between Aomori and Ōminato (a seasonal service).
• 197323 September: a concentrated downpour washes out the roadbed and breaches embankments at 78 points, suspending services; the line reopens on 13 December, 80 days later.
• 197411 May: the last scheduled steam-locomotive working runs, marking the end of steam on every railway in Aomori Prefecture.
• 19841 February: all freight operations on the line cease.
• 19871 April: with the breakup and privatisation of Japanese National Railways, the East Japan Railway Company succeeds to the line as a Type-1 railway operator.
• 198813 March: one-man operation begins; the rapid Natsudomari is renamed the Usori.
• 19931 December: KiHa 100 series diesel railcars are introduced; the rapid Usori is renamed the Shimokita.
• 19988 December: the line's token block working — JR East's last — is abolished in favour of a special automatic block system.
• 20021 December: with the Tōhoku Shinkansen extended to Hachinohe, one Shimokita rapid is extended through to Hachinohe Station; the joyful train Kirakira Michinoku also begins running.
• 20104 December: the Tōhoku Shinkansen is extended Hachinohe–Shin-Aomori and the parallel Hachinohe–Aomori section of the Tōhoku Main Line (including Noheji) passes to the Aoimori Railway, isolating the Ōminato Line from the rest of JR East; the hybrid resort train Resort Asunaro Shimokita (HB-E300 series) begins running.
• 202113 March: from the timetable revision, all scheduled trains become one-man-operated.