The Korean Empire intended to build the Gyeongui Line itself at the end of the 19th century, but a shortage of funding resulted in the project's suspension.

[1] The Empire of Japan, which gained a concession to build the Gyeongbu Line from Busan to Seoul, also sought to gain control of the Gyeongui Line project as its continuation further north, recognizing the trunk route as a means to keep Korea under its influence.

The DPRK sector is now 100% electrified, although the double track section spans only from Pyongyang to Sunan Airport.

[3] According to South Korean representatives, the North has agreed in principle to regular passenger and freight service along the two train lines.

[5] On 30 November 2018 an engineers' inspection train from South Korea crossed the border at Dorasan for an assessment, conducted jointly with North Korean officials, of the North's Kaesong to Sinuiju (P'yŏngŭi) line, and rail routes northwards from Mount Kumgang.

[citation needed] Meanwhile, work began to upgrade the South Korean section for high-capacity commuter services.

Between Seoul and Munsan, the line is converted into an electrified, double-tracked railway in a new, straighter, 48.6 km long alignment.

[6] As of 2009, construction progress on the entire Seoul–Munsan section reached 74% of a total budget then estimated at 2,153.271 billion won.

The outer portion of the line runs largely through countryside rice paddies, forests, and vegetable fields, and outside of Seoul rarely enters urbanized areas.