Administrative districts are governmental units for local administration, but at the same time they define regional and local identity. Since the nation’s founding, Korea has promoted administrative efficiency though a number of administrative reorganizations. In the midst of these changes, a do-oriented (province-oriented) administrative district system of the Joseon Dynasty is the basis for the modern metropolitan administrative system in Korea. The administrative system is comprised of 1 special city, 15 dos (provinces), 23 bus (cities), 208 guns (counties) in 1945. The following year, Jeju Island was separated from Jeollanam-do, and bu became si in 1948.
The Korean government carried out comprehensive reform to harmonize living spaces and administrative districts in 1962. For example, Geumsan-gun in Jeollabuk-do was transferred into Chungcheongnamdo, and Uljin-gun in Gangwon-do was merged into Gyeongsangbuk-do. The reforms after 1960 mainly took place due to urban expansion caused by population growth in cities and suburbanization. Small towns attained cityhood as their population increased, and major cities were promoted to directly-controlled municipalities so that the central government could manage them directly. During the 1960s, as Busan was promoted to a directly-controlled city, Korea consisted of 1 special city (Seoul), 1 directlycontrolled city (Busan Directly-Controlled City), 9 dos (Gyeonggi-do, Gangwon-do, Chungcheongbukdo, Chungcheongnam-do, Jeollabuk-do, Jeollanamdo, Gyeongsangbuk-do, Gyeongsangnam-do, and Jeju-do), 30 sis (cities), and 140 guns (counties). Large provincial cities, like Incheon, Daegu, Gwangju, and Daejeon, became directly-controlled cities in the 1980s. Subsequently, in 1995, overall provincial administrative reform was carried out. This reshuffling integrated cities and counties and aimed at balancing development between growing urban and declining rural areas, securing land for urban development, promoting administrative efficiency, and addressing inconsistencies between spaces of daily life and administrative districts. Also, directly-controlled municipalities were reorganized into metropolitan cities by combining neighboring areas. In 1995, forty urban rural integration cities were established and 5 metropolitan cities were created including Busan, Daegu, Incheon, and Daejeon. Ulsan attained metropolitan cityhood in 1997.
After the year 2000, continuous merging of cities and counties took place, and Jeju Island was raised to the status of a Jeju Special Self-governing Province. Sejong, a multifunctional administrative city, became the Sejong Metropolitan Autonomous City in 2012. As of January 1, 2014, the Republic of Korea has 1 teukbyeol-si (special city), 6 gwangyeoksis (metropolitan cities), 1 teukbyeol Jachi-si (special autonomous city), 8 dos (provinces), and 1 teukbyeol Jachi-do (special self-governing autonomous province).