# Seoul City Route 21 (Trunk)

Seoul Metropolitan City Route 21 (Korean: 서울특별시도 제21호선) is a road located in Seoul, South Korea. With a total length of 17.7 km (11.0 mi), this road starts from the Siheung-dong in Geumcheon District, Seoul to Jungnim-dong in Jung District.

## Stopovers
### Seoul

* Geumcheon District - Gwanak District - Guro District - Dongjak District - Yeongdeungpo District - Yongsan District - Jung District

## List of Facilities

IS: Intersection, IC: Interchange
* (■): National Route 1 overlap
| Road name | Name | Hangul name | Connection | Location | Location | Location | Location | Note |
| Connected with Gyeongsu-daero |||||||||
| Siheung-daero | | | National Route 1 Gyeongsu-daero | Geumcheon District | Geumcheon District | Siheung 3-dong | Siheung 3-dong | |
| Siheung-daero | | | Samseongsan-gil | Geumcheon District | Geumcheon District | Siheung 3-dong | Siheung 3-dong | Unnamed |
| Siheung-daero | | | Siheung-daero 6-gil | Geumcheon District | Geumcheon District | Siheung 3-dong | Siheung 3-dong | Unnamed |
| Siheung-daero | | | Siheung-daero 8-gil | Geumcheon District | Geumcheon District | Siheung 3-dong | Siheung 3-dong | Unnamed |
| Siheung-daero | Gia Bridge | 기아대교앞 | Gia-ro | Geumcheon District | Geumcheon District | Siheung 3-dong | Siheung 3-dong | |
| Siheung-daero | | | Siheung-daero 28-gil | Geumcheon District | Geumcheon District | Siheung 3-dong | Siheung 3-dong | Unnamed |
| Siheung-daero | | | Siheung-daero 36-gil | Geumcheon District | Geumcheon District | Siheung 3-dong | Siheung 3-dong | Unnamed |
| Siheung-daero | | | Siheung-daero 39-gil | Geumcheon District | Geumcheon District | Siheung 3-dong | Siheung 1-dong | Unnamed |
| Siheung-daero | Bakmi IS | 박미삼거리 | Doksan-ro | Geumcheon District | Geumcheon District | Siheung 5-dong | Siheung 1-dong | |
| Siheung-daero | | | Eunpyeongnamu-ro | Geumcheon District | Geumcheon District | Siheung 1-dong | Siheung 1-dong | Unnamed |
| Siheung-daero | | | Siheung-daero 51-gil | Geumcheon District | Geumcheon District | Siheung 1-dong | Siheung 1-dong | Unnamed |
| Siheung-daero | Siheung IS | 시흥사거리 | National Route 1 Geumha-ro | Geumcheon District | Geumcheon District | Siheung 1-dong | Siheung 1-dong | |
| Siheung-daero | Geumcheon-gu Office Entrance | 금천구청입구 | Siheung-daero 71-gil | Geumcheon District | Geumcheon District | Siheung 1-dong | Siheung 1-dong | |
| Siheung-daero | Geumcheon-gu Office Entrance | | Siheung-daero 73-gil | Geumcheon District | Geumcheon District | Siheung 1-dong | Siheung 1-dong | |
| Siheung-daero | | | Siheung-daero 90-gil | Geumcheon District | Geumcheon District | Doksan 1-dong | Doksan 2-dong | Unnamed |
| Siheung-daero | Malmi IS | 말미사거리 | Beoman-ro | Geumcheon District | Geumcheon District | Doksan 1-dong | Doksan 2-dong | |
| Siheung-daero | Malmi IS | | Beoman-ro | Geumcheon District | Geumcheon District | Doksan 1-dong | Doksan 4-dong | |
| Siheung-daero | Geumcheon Post Office | 금천우체국 | Dusan-ro | Geumcheon District | Geumcheon District | Doksan 1-dong | Doksan 4-dong | |
| Siheung-daero | Geumcheon Post Office | | Siheung-daero 122-gil | Geumcheon District | Geumcheon District | Doksan 1-dong | Doksan 4-dong | |
| Siheung-daero | Doksan IS | 독산사거리 | Gasan-ro | Geumcheon District | Geumcheon District | Doksan 1-dong | Doksan 4-dong | |
| Siheung-daero | Doksan IS | | Gasan-ro | Geumcheon District | Geumcheon District | Doksan 1-dong | Doksan 3-dong | |
| Siheung-daero | | | Siheung-daero 150-gil | Geumcheon District | Geumcheon District | Doksan 1-dong | Doksan 3-dong | Unnamed |
| Siheung-daero | Siheung IC | 시흥나들목 | Nambu Beltway | Geumcheon District | Geumcheon District | Doksan 1-dong | Doksan 3-dong | |
| Siheung-daero | Siheung IC | | Digital-ro 31ga-gil | Geumcheon District | Geumcheon District | Doksan 1-dong | Doksan 3-dong | |
| Siheung-daero | Siheung IC | | Siheung-daero 161-gil | Guro District | Guro 3-dong | Gwanak District | Jowon-dong | |
| Siheung-daero | Siheung IC | | Siheung-daero 161ga-gil | Guro District | Guro 3-dong | Gwanak District | Jowon-dong | |
| Siheung-daero | Digital Complex Entrance | 디지털단지입구 | Digital-ro 32-gil | Guro District | Guro 3-dong | Gwanak District | Jowon-dong | |
| Siheung-daero | Digital Complex Entrance | | Siheung-daero 164-gil | Guro District | Guro 3-dong | Gwanak District | Jowon-dong | |
| Siheung-daero | Guro Digital Complex station | 구로디지털단지역 | Sinsa-ro | Guro District | Guro 3-dong | Gwanak District | Jowon-dong | |
| Siheung-daero | Guro Bridge (Dorimcheon) | 구로교 (도림천) | | Guro District | Guro 3-dong | Gwanak District | Jowon-dong | |
| Siheung-daero | Guro Bridge (Dorimcheon) | | | Yeongdeungpo District | Daerim 2-dong | Dongjak District | Sindaebang 1-dong | |
| Siheung-daero | Daerim IS | 대림사거리 | Daerim-ro | Yeongdeungpo District | Daerim 2-dong | Dongjak District | Sindaebang 1-dong | |
| Siheung-daero | Daerim IS | | Daerim-ro | Yeongdeungpo District | Daerim 1-dong | Dongjak District | Sindaebang 1-dong | |
| Siheung-daero | | | Siheung-daero 187-gil | Yeongdeungpo District | Daerim 1-dong | Dongjak District | Sindaebang 1-dong | Unnamed |
| Siheung-daero | Daerim IS | 대림삼거리 | Singil-ro | Yeongdeungpo District | Daerim 1-dong | Dongjak District | Sindaebang 1-dong | |
| Yeouidaebang-ro | Daerim IS | | Singil-ro | Yeongdeungpo District | Singil 6-dong | Dongjak District | Sindaebang 1-dong | |
| Yeouidaebang-ro | | | Yeouidodaebang-ro 2-gil | Yeongdeungpo District | Singil 6-dong | Dongjak District | Sindaebang 1-dong | Unnamed |
| Yeouidaebang-ro | | | Yeouidodaebang-ro 10-gil | Yeongdeungpo District | Singil 6-dong | Dongjak District | Sindaebang 1-dong | Unnamed |
| Yeouidaebang-ro | | | Yeouidodaebang-ro 10-gil | Yeongdeungpo District | Singil 6-dong | Dongjak District | Sindaebang 2-dong | Unnamed |
| Yeouidaebang-ro | Boramae Park Entrance | 보라매공원입구 | Yeouidodaebang-ro 20-gil | Yeongdeungpo District | Singil 6-dong | Dongjak District | Sindaebang 2-dong | |
| Yeouidaebang-ro | Daebangcheon IS | 대방천사거리 | Daebangcheon-ro | Yeongdeungpo District | Singil 6-dong | Dongjak District | Sindaebang 2-dong | |
| Yeouidaebang-ro | Daebangcheon IS | | Yeouidodaebang-ro 24-gil | Yeongdeungpo District | Singil 6-dong | Dongjak District | Daebang-dong | |
| Yeouidaebang-ro | Boramae station | 보라매역 | Sangdo-ro | Yeongdeungpo District | Singil 6-dong | Dongjak District | Daebang-dong | |
| Yeouidaebang-ro | Boramae station | | Sinpung-ro | Yeongdeungpo District | Singil 6-dong | Dongjak District | Daebang-dong | |
| Yeouidaebang-ro | Navy Hall | 해군회관앞 | Gamasan-ro | Yeongdeungpo District | Singil 7-dong | Dongjak District | Daebang-dong | |
| Yeouidaebang-ro | Navy Hall | | Yeouidodaebang-ro 36-gil | Yeongdeungpo District | Singil 7-dong | Dongjak District | Daebang-dong | |
| Yeouidaebang-ro | Sungnam High School Entrance | 성남고교입구 | Yeouidodaebang-ro 43-gil | Yeongdeungpo District | Singil 7-dong | Dongjak District | Daebang-dong | |
| Yeouidaebang-ro | | | Yeouidodaebang-ro 46-gil | Yeongdeungpo District | Singil 7-dong | Dongjak District | Daebang-dong | Unnamed |
| Yeouidaebang-ro | | | Yeouidodaebang-ro 49-gil | Yeongdeungpo District | Singil 7-dong | Dongjak District | Daebang-dong | Unnamed |
| Yeouidaebang-ro | Daebang Underpass (Gyeongbu Line) | 대방지하차도 (경부선) | | Yeongdeungpo District | Yeongdeungpo District | Singil 7-dong | Singil 7-dong | |
| Yeouidaebang-ro | Yeoui Bridge (Yeouido Saetgang) | 여의교 (샛강) | | Dongjak District | Dongjak District | Daebang-dong | Daebang-dong | |
| Yeouidaebang-ro | Yeoui Bridge (Yeouido Saetgang) | | | Yeongdeungpo District | Yeongdeungpo District | Yeoui-dong | Yeoui-dong | |
| Yeouidaebang-ro | Yeoui Bridge IS | 여의교오거리 | Uisadang-daero | Yeongdeungpo District | Yeongdeungpo District | Yeoui-dong | Yeoui-dong | |
| Yeouidaebang-ro | Yeoui Bridge IS | | Yeouidong-ro | Yeongdeungpo District | Yeongdeungpo District | Yeoui-dong | Yeoui-dong | |
| Yeouidaebang-ro | | | Yeouidodaebang-ro 65-gil | Yeongdeungpo District | Yeongdeungpo District | Yeoui-dong | Yeoui-dong | Unnamed |
| Yeouidaebang-ro | Hanyang Apartment | 한양아파트앞 | Gukjegeumyung-ro | Yeongdeungpo District | Yeongdeungpo District | Yeoui-dong | Yeoui-dong | |
| Yeouidaebang-ro | Wonhyo Bridge (Hangang) | 원효대교 (한강) | | Yeongdeungpo District | Yeongdeungpo District | Yeoui-dong | Yeoui-dong | |
| Cheongpa-ro | Wonhyo Bridge (Hangang) | | | Yongsan District | Yongsan District | Wonhyoro 2-dong | Ichon 2-dong | |
| Cheongpa-ro | | | Wonhyo-ro | Yongsan District | Yongsan District | Hangangro-dong | Hangangro-dong | Unnamed |
| Cheongpa-ro | | | Cheongpa-ro 20-gil | Yongsan District | Yongsan District | Hangangro-dong | Hangangro-dong | Unnamed |
| Cheongpa-ro | Yongsan Electronics Market | 용산전자상가 | Saechang-ro | Yongsan District | Yongsan District | Hangangro-dong | Hangangro-dong | |
| Cheongpa-ro | Ukcheon Overpass (Yongsan Line) | 욱천고가 (용산선) | | Yongsan District | Yongsan District | Hangangro-dong | Hangangro-dong | |
| Cheongpa-ro | Ukcheon Overpass (Yongsan Line) | | | Yongsan District | Yongsan District | Wonhyoro 1-dong | Wonhyoro 1-dong | |
| Cheongpa-ro | | | Wonhyo-ro 90-gil | Yongsan District | Yongsan District | Wonhyoro 1-dong | Wonhyoro 1-dong | Unnamed |
| Cheongpa-ro | Namyeong station | 남영역 | Wonhyo-ro | Yongsan District | Yongsan District | Wonhyoro 1-dong | Wonhyoro 1-dong | |
| Cheongpa-ro | Namyeong station | | Hangang-daero 77-gil | Yongsan District | Yongsan District | Cheongpa-dong | Cheongpa-dong | |
| Cheongpa-ro | | | Cheongpa-ro 45-gil | Yongsan District | Yongsan District | Cheongpa-dong | Cheongpa-dong | Unnamed |
| Cheongpa-ro | | | Hangang-daero 87-gil | Yongsan District | Yongsan District | Cheongpa-dong | Cheongpa-dong | Unnamed |
| Cheongpa-ro | Sookmyung Women's University Entrance | 숙명여대입구 | Cheongpa-ro 47-gil | Yongsan District | Yongsan District | Cheongpa-dong | Cheongpa-dong | |
| Cheongpa-ro | | | Cheongpa-ro 71-gil | Yongsan District | Yongsan District | Cheongpa-dong | Cheongpa-dong | Unnamed |
| Cheongpa-ro | | | Cheongpa-ro 85-gil | Yongsan District | Yongsan District | Cheongpa-dong | Namyeong-dong | Unnamed |
| Cheongpa-ro | Seoul Station (West) | 서울역서부 | Mallijae-ro | Jung District | Jung District | Jungnim-dong | Hoehyeon-dong | |
| Cheongpa-ro | Seoul Station (West) | | Jungnim-ro | Jung District | Jung District | Jungnim-dong | Hoehyeon-dong | |
| Cheongpa-ro | Jungnim-dong IS | 중림동삼거리 | Chilpae-ro | Jung District | Jung District | Jungnim-dong | Hoehyeon-dong | |
| Cheongpa-ro | Jungnim-dong IS | | Cheongpa-ro 103-gil | Jung District | Jung District | Jungnim-dong | Hoehyeon-dong | |
| Cheongpa-ro | Seoul Waterworks Office IS | 상수도사업본부삼거리 | Seosomun-ro | Jung District | Jung District | Jungnim-dong | Jungnim-dong | |