The Gyeongin Expressway, officially Expressway No. 120, is a tolled controlled-access highway connecting the Yangcheon District of Seoul to the Nam District of Incheon. It is the oldest expressway in South Korea.
Construction began March 24, 1967. The initial segment between Gajwa in the Seo District of Incheon and Yangpyeong-dong in the Yeongdeungpo District of Seoul opened on December 21, 1968. In 1985, the easternmost segment between Yangpyeong and the Shinwol Interchange was transferred to Seoul, making Shinwol in the Yancheong District the new terminus.
It was assigned route number 2 in 1983. In 2001, South Korea re-rationalized its expressway numbering system, and it was redesignated route 120.