On 1 August 1940, a branch from Bukpyeong (today Donghae Station) to Mukho bypassing Mukho Port was opened, and the original alignment became the Mukho Port Line (ko); this was followed by a 12 kilometers branch from Bukpyeong to Samcheok, the Samcheok Line (ko), that was opened on 11 February 1944.