Akō Line

The line was built by the Japanese National Railways (JNR) in the years after the Second World War and was opened in stages over little more than a decade. The first section, between Aioi and Banshū-Akō, opened on 12 December 1951, a distance of 10.5 kilometres; two weeks later, on 26 December 1951, through services began running between Himeji and Banshū-Akō over the new line and the Sanyō Main Line.

Construction then pushed westward along the coast. The line was extended from Banshū-Akō to Hinase on 1 March 1955, adding 11.6 kilometres, and on from Hinase to Inbe on 25 March 1958, a further 12.4 kilometres. The final 22.9-kilometre section, from Inbe through to Higashi-Okayama, opened on 1 September 1962, completing the through route between Aioi and Higashi-Okayama and giving trains a second corridor between the Himeji and Okayama areas.

Electrification followed the construction in two phases. The eastern Aioi–Banshū-Akō section was electrified at 1,500 V DC on 30 March 1961, ahead of the line's full opening. The remaining, longer western portion between Banshū-Akō and Higashi-Okayama was not electrified until 24 August 1969, at which point the entire Akō Line was under wire and through electric operation across its whole length became possible.

Through the 1960s the line continued to fill out: intermediate stations were added as the surrounding towns grew, with Sako Station opening on 1 April 1962, Tenwa and Nishi-Katakami stations on 1 May 1963, and the Nishihama signal station established on 1 October 1966. Centralised traffic control (CTC) was commissioned over the Banshū-Akō–Higashi-Okayama section on 29 July 1983, allowing train movements on the western part of the line to be supervised remotely.

With the privatisation and division of the Japanese National Railways on 1 April 1987, the Akō Line passed to the newly formed West Japan Railway Company, which has operated it ever since; Japan Freight Railway (JR Freight) holds running rights for freight service over the line. In the JR West era the eastern end was integrated into the company's Urban Network around the Kansai region, and from 16 March 1996 Special Rapid (shinkaisoku) services were extended onto the Aioi–Banshū-Akō section during the evening rush, later expanded to daytime hours before being scaled back to peak periods.

More recent decades have brought service and systems upgrades typical of a regional JR West line. IC card use with ICOCA began on 1 November 2003 and was extended across the whole line by 15 September 2018; one-person (wanman) operation was introduced on the Banshū-Akō–Okayama section from 16 October 2004; and the line received the company's new 227-series "Urara" suburban trains, whose 500-subseries entered service on 12 October 2025.

• 195112 December: the first section, Aioi–Banshū-Akō (10.5 km), opens.
• 195126 December: through services begin between Himeji and Banshū-Akō via the new line and the Sanyō Main Line.
• 19551 March: the line is extended from Banshū-Akō to Hinase (11.6 km).
• 195825 March: the line is extended from Hinase to Inbe (12.4 km).
• 196130 March: the Aioi–Banshū-Akō section is electrified at 1,500 V DC.
• 19621 April: Sako Station opens.
• 19621 September: the final Inbe–Higashi-Okayama section (22.9 km) opens, completing the through route between Aioi and Higashi-Okayama.
• 19631 May: Tenwa and Nishi-Katakami stations open.
• 19661 October: the Nishihama signal station is established.
• 196924 August: the Banshū-Akō–Higashi-Okayama section is electrified, completing electrification of the whole line.
• 198329 July: centralised traffic control (CTC) is commissioned over the Banshū-Akō–Higashi-Okayama section.
• 19871 April: with the privatisation and division of Japanese National Railways, the line passes to JR West (with JR Freight holding running rights).
• 199616 March: Special Rapid (shinkaisoku) services are extended onto the Aioi–Banshū-Akō section during the evening rush.
• 20031 November: ICOCA IC card service begins on the line.
• 200416 October: one-person (wanman) operation begins on the Banshū-Akō–Okayama section.
• 201815 September: ICOCA support is completed across the entire line.