Seoul Subway Line 4 (dubbed The Blue Line) of the Seoul Metropolitan Subway is a long line crossing from the southwest to the northeast across the Seoul National Capital Area. The central section in Seoul City is operated by Seoul Metro with some trains offering through service to Korail's Ansan and Gwacheon Lines. The southern terminus (Oido) is in Jeongwang 4-dong, Siheung City, and the northern terminus (Danggogae) is in Sanggye 4-dong, Nowon-gu, northern Seoul. In 2019, the Seoul Metro operated section had an annual ridership of 327 million or about 895,000 passengers per day.