The six-lane bridge connecting it to the mainland of Yeongdeungpo was built in 1970 as part of Han River development project led by President Park Jung-Hee, after which followed a period of rapid development. Formerly part of Goyang, Yeouido-dong was formed as a separate entity in 1971. In 1975 the new National Assembly Building opened on the western side of the island. In 1983 the 63 building was completed and was the tallest and most well-known building in the country for many years.