Aterazawa Line

The line was built as a light railway. Its first section, the 12.9-kilometre stretch from Yamagata to Uzen-Nagasaki, opened on 20 July 1921 as the Aterazawa Light Line (左沢軽便線). It was extended a further 4.4 kilometres from Uzen-Nagasaki to Sagae on 11 December of the same year.

The remaining 8.9-kilometre section from Sagae onward to Aterazawa opened on 23 April 1922, completing the through route from Yamagata to Aterazawa. On 2 September 1922 the line was renamed simply the Aterazawa Line. In 1927 Ōu Main Line trains began stopping at Kita-Yamagata.

On 25 December 1951 five new stations were opened along the route in a single day, doubling the number of stations. From 1 April 1958 all trains except one mixed-train round trip were worked by diesel railcars.

In March 1982 centralised traffic control (CTC) was introduced, with the control centre placed at Kita-Yamagata. Later that year, on 5 November 1982, freight operations over the whole line were abolished, leaving it a purely passenger railway. On 1 April 1987 the line passed from the Japanese National Railways to the newly formed JR East under the division and privatisation of JNR.

Under JR East, one-man (driver-only) operation began across the whole line on 10 March 1990, and a dedicated Aterazawa Line operating office was established. On 2 July 1998 the official line section was redefined as running from Kita-Yamagata to Aterazawa, although Aterazawa Line trains continued to run through to Yamagata.

The line's wrought-iron Warren-truss bridge over the Mogami River, the Mogami-gawa Kyōryō, was recognised in 2008 as a Civil Engineering Heritage by the Japan Society of Civil Engineers. Services were suspended for a time after the Tōhoku earthquake of 11 March 2011 before being restored. Suica IC-card acceptance was introduced on the Kita-Yamagata–Sagae section on 16 March 2024. Its trains are Kiha 101 diesel railcars, and it is used mainly by commuters and students travelling to Yamagata.

11 stations tracked on the map, listed alphabetically. Select any to read its page.

• Aterazawa左沢
• Higashi-Kanai東金井
• Kita-Yamagata北山形
• Minami-Sagae南寒河江
• Nishi-Sagae西寒河江
• Sagae寒河江
• Shibahashi柴橋
• Uzen-Kanezawa羽前金沢
• Uzen-Nagasaki羽前長崎
• Uzen-Takamatsu羽前高松
• Uzen-Yamabe羽前山辺

• 192120 July: the first section, Yamagata–Uzen-Nagasaki (12.9 km), opens as the Aterazawa Light Line (左沢軽便線).
• 192111 December: the line is extended from Uzen-Nagasaki to Sagae (4.4 km).
• 192223 April: the Sagae–Aterazawa section (8.9 km) opens, completing the through route from Yamagata to Aterazawa.
• 19222 September: the Yamagata–Aterazawa route is renamed the Aterazawa Line.
• 192711 September: Ōu Main Line trains begin stopping at Kita-Yamagata Station.
• 195125 December: five new stations open in a single day, doubling the number of stations on the line.
• 19581 April: all services except one mixed-train round trip are converted to diesel railcar operation.
• 1982March: centralised traffic control (CTC) is commissioned, with the control centre at Kita-Yamagata.
• 19825 November: freight operations over the whole line are abolished, leaving it a passenger-only railway.
• 19871 April: under the division and privatisation of JNR, the line passes to the newly formed JR East.
• 199010 March: one-man (driver-only) operation begins across the whole line; a dedicated Aterazawa Line operating office is established.
• 19982 July: the official line section is redefined as Kita-Yamagata–Aterazawa.
• 2008The Mogami River Bridge (最上川橋梁) is selected as a Civil Engineering Heritage by the Japan Society of Civil Engineers.
• 201111 March: the line is suspended throughout following the 2011 Tōhoku earthquake, before later being restored.
• 202416 March: Suica IC-card service begins on the Kita-Yamagata–Sagae section.