The Nambu Line (南武線) is a main line run by East Japan Railway Company (JR East). It links Kawasaki Station in Kawasaki, Kanagawa, with Tachikawa Station in Tachikawa, Tokyo.
History
The Nambu Line began as a private railway, the Nambu Railway (南武鉄道). In 1919 Akimoto Kishiro, a village council member, applied to the Railway Bureau for a licence to build a railway that would carry gravel from the bed of the Tama River. A licence was granted on 29 January 1920, and the company was renamed Nambu Railway. The Asano group joined because it wanted to carry limestone to its cement factory in Kawasaki, and Asano Taijiro became the largest shareholder on 30 September 1923. The first section, from Kawasaki to Noborito, opened on 9 March 1927 and was electrified. The line reached Tachikawa on 11 December 1929. The branch from Tejima to Hamakawasaki opened in 1930.
In the 1930s factories were built along the line, and the railway carried commuters to them. The Kawasaki to Musashi-Mizonokuchi section was double tracked by 1939. During the Pacific War the railway also carried military transport, because military facilities were built along the line. Japanese Wikipedia says the line linked the Tokaido Line with industrial areas and carried limestone. On 1 April 1944 the Nambu Railway was nationalised under the wartime rules for buying private railways, and it became the Nambu Line. Air raids damaged the line in April 1945, and by November 1945 fewer than half of its cars could run.
On 1 June 1949 the line passed to Japanese National Railways (JNR). On 7 August 1962 a train hit a small truck at a crossing and derailed, and an oncoming train then hit it. Three people died and 154 were injured. Traffic grew in the 1950s as Tokyo's wards expanded, and the line was double tracked in stages. In the late 1960s trains were lengthened to six cars, and the whole line was double tracked on 30 September 1966, except inside Tachikawa Station. On 15 December 1969 the line borrowed 101 series cars and began rapid trains.
On 8 March 1976 the line received 101 series cars from the Keihin-Tohoku Line, and six-car trains began running on the main line. By 1978 all trains on the line were 101 series six-car sets. The 103 series entered service in 1982. The 205 series began on 11 March 1989. On 20 December 1990 the elevated track between Musashi-Kosugi and Musashi-Mizonokuchi was completed. The 101 series made its last six-car run on the main line in January 1991. The 209 series began in April 1993. On 9 October 2005 the elevated section between Inadagutsumi and Inagi-Naganuma was completed.
On 1 April 1987 the national railway was split up, and East Japan Railway Company (JR East) took over the Nambu Line. On 24 October 1999 a new platform at Tachikawa Station removed the bottleneck there, and the whole line was double track. On 4 October 2014 the E233 series began service. On 14 March 2015 rapid trains were extended to run the full route from Kawasaki to Tachikawa. On 15 March 2017 the E233 series became the only type used on the main line.
On 11 March 2011 the Great East Japan Earthquake struck and the line was suspended all day. On 14 March 2011 Tokyo Electric Power carried out rolling blackouts, and the line was suspended all day again. Rapid service resumed on 9 April 2011, after being delayed by the earthquake. In the 2020s the line often appeared in rankings of crowded lines in the Tokyo area, and rush-hour crowding became a problem. On 15 March 2025 one-man operation started between Kawasaki and Tachikawa. On 1 July 2026 the railway changed from regional branches to business headquarters, and the line's sections were placed under the Kawasaki, Musashino and Tachikawa headquarters.
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Written by an AI from the line's history on Japanese Wikipedia, nothing else, and checked by a program for dates and numbers that are not in those facts. It can still be wrong. Adapted from Japanese Wikipedia, CC BY-SA 4.0; this text is shared under the same licence.