Kawagoe Line

A railway linking Ōmiya with Kawagoe and continuing to meet the Hachikō Line at Komagawa was first proposed in March 1920. Construction did not begin until September 1935, and the line finally opened on 22 July 1940, running the full 30.6 km from Ōmiya to Komagawa with eight stations: Nisshin, Sashiōgi, Minami-Furuya, Kawagoe, Nishi-Kawagoe, Matoba, Kasahata and Musashi-Takahagi. The new line gave the established castle town of Kawagoe a direct rail connection to Ōmiya and, by way of the Hachikō Line at Komagawa, a route around the western edge of the Tokyo conurbation.

Services were steam-hauled at first. From 1 June 1950 diesel multiple units were introduced, modernising the line's motive power, and the final steam-hauled passenger train ran on 30 September 1969, after which operation was fully dieselised.

The line's transformation came in the mid-1980s. On 30 September 1985 the whole Kawagoe Line was electrified at 1,500 V DC, the Ōmiya–Nisshin section was double-tracked, and a new electric-multiple-unit depot was opened near Minami-Furuya Station. The same day, the Saikyō Line opened, and through running began between the Ōmiya–Kawagoe section and the Saikyō Line, integrating the eastern half of the Kawagoe Line into a new commuter corridor reaching central Tokyo.

With the privatisation of Japanese National Railways on 1 April 1987, the line passed to the newly formed East Japan Railway Company, and freight operations over the whole line were discontinued at the same time.

Through running was extended at both ends in the years that followed. On 16 March 1996, after the southern part of the Hachikō Line between Komagawa and Hachiōji was electrified, through services began between Kawagoe and Hachiōji over the Hachikō Line, giving the western Kawagoe–Komagawa section its present operating partner. On 1 December 2002, services from the eastern section were extended beyond the Saikyō Line into the new Rinkai Line of the Tokyo Waterfront Area Rapid Transit, reaching Shin-Kiba on Tokyo Bay.

The line has continued to gain wider connections in the 21st century. From 30 November 2019, a small number of early-morning trains began through running onto the Sōtetsu network in Kanagawa, by way of the Saikyō and Rinkai lines, further extending the reach of the eastern section. Today the Kawagoe Line functions as two linked commuter services: a frequent, double-track-aided Ōmiya–Kawagoe service tied into the Saikyō and Rinkai lines toward central and bayside Tokyo, and a quieter Kawagoe–Komagawa service through-running with the Hachikō Line, with passengers changing at Kawagoe to travel the full length.

• 1920March: a railway linking Ōmiya with Kawagoe and continuing to the Hachikō Line at Komagawa is first proposed.
• 1935September: construction of the line begins.
• 194022 July: the full Ōmiya–Komagawa line (30.6 km) opens with eight stations — Nisshin, Sashiōgi, Minami-Furuya, Kawagoe, Nishi-Kawagoe, Matoba, Kasahata and Musashi-Takahagi.
• 19501 June: diesel multiple units are introduced, modernising the line's motive power from steam.
• 196930 September: the final steam-hauled passenger train runs; operation thereafter is fully dieselised.
• 198530 September: the whole line is electrified at 1,500 V DC, the Ōmiya–Nisshin section is double-tracked, a new EMU depot opens near Minami-Furuya, and through running with the Saikyō Line (which opens the same day) begins on the Ōmiya–Kawagoe section.
• 19871 April: with the privatisation of Japanese National Railways, the line passes to JR East; freight operations over the whole line are discontinued.
• 199616 March: following electrification of the Komagawa–Hachiōji section of the Hachikō Line, through services begin between Kawagoe and Hachiōji over the Hachikō Line.
• 20021 December: through running begins with the Rinkai Line of the Tokyo Waterfront Area Rapid Transit via the Saikyō Line, extending eastern-section trains to Shin-Kiba.
• 201930 November: a few early-morning trains begin through running onto the Sōtetsu network via the Saikyō and Rinkai lines.