Hamgyong Line - Environmental Line

Japanese: 咸鏡線 - かんきょうせん

...It developed as a commercial city with the agricultural region of the Hamhung Plain as a backdrop, and grain and cattle markets were particularly bustling. When the Hamgyong Line (Wonsan to Hoeryong) was opened in 1928 during the Japanese colonial period, it became a major intermediate station and the starting point of the industrial railway to the Gaema Plateau in the northern hinterland. After 1929, when the two major hydroelectric power plants on the Bujeon River and the Changjin River were completed, the Noguchi Group (Noguchi Jun) built various chemical plants, including a large nitrogen fertilizer plant, in the neighboring Hungnam area on the basis of these plants, and it quickly developed into North Korea's largest heavy chemical industrial area. ...

From Rajin

…It has Rajin Port, a good natural harbor that does not require icebreakers even in winter. In 1932, the Hamgyong Line (Wonsan to Hoeryong) finally reached the city, but it was the most remote area on the railroad and remained a small fishing village. In 1965, the Cheongra Line was completed, directly connecting it to Chongjin, and urbanization progressed as a transportation hub, and it was promoted to a city in 1967. …

*Some of the terminology that refers to the "Hamgyong Line" is listed below.

Source | Heibonsha World Encyclopedia 2nd Edition | Information

Japanese:

…咸興平野の農業地帯を背景に商業都市として発達し，とくに穀物や牛の市がにぎわったところである。日本植民地時代の1928年に咸鏡線(元山～会寧)が開通すると，中間の主要駅となり，北方奥地の蓋馬（かいま）高原方面に至る産業鉄道の発着点となった。29年以後赴戦江および長津江の二大水力発電所が完成すると，これを基礎に隣接の興南地域に野口財閥(野口遵（したがう）)によって大型の窒素肥料工場をはじめ各種の化学工場が建設されるようになり，またたくまに北朝鮮最大の重化学工業地帯に発達した。…