The name Gyeongin (경인 (京仁) in Korean) refers to the Seoul-Incheon corridor in South Korea, and is used as the name of the Gyeongin railway line (Gyeonginseon; 경인선; 京仁先) and Gyeongin Expressway (Gyeongin Gosok Doro; 경인 고속 도로; 京仁高速道路), both of which link Seoul--the South Korean capital and largest city--to nearby Incheon--the second-largest port and fourth-largest city. The name "Gyeongin" is formed from the first characters in the names "Gyeongseong" (경성 (京成), the Korean form of "Keijo" (京成), the former Japanese name for Seoul) and "Incheon" (인천 (仁川)).