Editing Seoul Subway Line 4 (section)

== History ==
1985:
:20 April: Line 4 is officially opened from Sanggye to Sadang.<ref name=":0">{{Cite web |title=개요 및 연혁 |trans-title=Overview and History |url=http://www.seoulmetro.co.kr/kr/page.do?menuIdx=512 |url-status=live |archive-url=https://web.archive.org/web/20240205120552/http://www.seoulmetro.co.kr/kr/page.do?menuIdx=512 |archive-date=5 February 2024 |access-date=12 July 2024 |website=seoulmetro.co.kr |language=ko}}</ref>

1993:
:21 April: The line is extended northward from Sanggye to Danggogae, and southward from Sadang to Namtaeryeong.<ref name=":0" />

1994:
:1 April: The line is extended southward from Sadang to Ansan when a section of the Gwacheon Line (from Seonbawi to Indeogwon) and Namtaeryeong station open.

2000:
:28 July: The line is extended westward from Ansan to Oido.

2003
:18 July: Surisan station opens as an in-fill station on the Ansan Line section.

2010
: Ansan Line AM express service is launched in the northbound direction only (starting from Ansan). Trains stopped at Jungang, Sangnoksu, and Sanbon, before continuing local up to Danggogae.

2014
: 1 September: Southbound PM express service is launched (terminating at Ansan). Trains make the same stops as their AM express service counterparts.

2017
: 7 July: Express service is extended to Oido. In addition to the stops they made before, trains make all stops between Ansan and Oido.

2020
: 12 September: Express service is modified, with trains now stopping at Choji but skipping Singiloncheon.

2022:
:19 March: The Jinjeop Line, a northward extension of Line 4, opens from Danggogae to Jinjeop.<ref>{{Cite web|url=https://gwanbo.go.kr/ezpdf/customLayout.jsp?contentId=I0000000000000001628061271815000&tocId=I0000000000000001627602304031000&isTocOrder=N&name=%25EA%25B5%25AD%25ED%2586%25A0%25EA%25B5%2590%25ED%2586%25B5%25EB%25B6%2580%25EA%25B3%25A0%25EC%258B%259C%25EC%25A0%259C2021-997%25ED%2598%25B8(%25EC%2582%25AC%25EC%2597%2585%25EC%259A%25A9%25EC%25B2%25A0%25EB%258F%2584%25EB%2585%25B8%25EC%2584%25A0%25EC%25A7%2580%25EC%25A0%2595%25EB%25B0%258F%25EC%25B2%25A0%25EB%258F%2584%25EA%25B1%25B0%25EB%25A6%25AC%25ED%2591%259C)|title = EzPDF WebViewer}}</ref>

=== Future ===
Express services are planned to start skipping various stations north of Sanbon station by 2023 to cut travel times.<ref>{{Cite web|url=http://www.joongboo.com/news/articleView.html?idxno=1178955|title=4호선 금정~사당 급행열차 추진된다|date=11 July 2017|website=중부일보 – 경기·인천의 든든한 친구}}</ref>