It was subsequently extended from Kaech'ŏn to Ch'ŏndong, with the new section being opened on 1 December 1918.

[3] Sentetsu began converting the Kaech'ŏn–Ch'ŏndong section to standard gauge, completing this work on 15 July 1933,[4] and on 1 September 1933 the entirety of the line was officially absorbed into Sentetsu, with the Kaech'ŏn–Ch'ŏndong section becoming part of the Manp'o Line.

After the partition of Korea the line was located in North Korea and became part of the Korean State Railway, which converted the remaining narrow-gauge section (Sinanju–Kaech'ŏn) to standard gauge in 1949;[1] the regauging work began in March 1949 and was completed in eight months.

[2] Anthracite and cement are the primary commodities shipped on the line.

[2] A yellow background in the "Distance" box indicates that section of the line is not electrified