The Namsi (now Yŏmju)-South Sinŭiju stretch of railway was opened on 5 November 1905 as part of the mainline of the Kyŏngŭi Line from Kyŏngsŏng (Seoul) to Sinŭiju.
After the establishment of the DPRK and the nationalisation of its railways to create the Korean State Railway, the line from Ryongch'ŏn (formerly Yangsi) to Yŏmju (formerly Namsi) remained separate as the Yangsi Line.