reasons given by new immigrants for coming to the capital. Other factors cited by immigrants included "education" and "a more convenient area to live." To alleviate overcrowding in Seoul's downtown area, the city government drew up a master plan in the mid-1980s that envisioned the development of four "core zones" by 2000: the original downtown area, Yongdongpo-Yeouido, Yongdong, and Jamsil. Satellite towns also would be established or expanded. In the late 1980s, statistics revealed that the daytime or commuter population of downtown Seoul was as much as six times the officially registered population. If the master plan is successful, many commuters will travel to work in a core area nearer their homes, and the downtown area's daytime population will decrease. Many government ministries have been moved out of Seoul, and the army, navy, and air force headquarters have been relocated to Daejeon. In 1985 the population of Seoul constituted 23.8% of the national total. Provincial cities, however, experienced equal and, in many cases, greater expansion than the capital. Growth was particularly spectacular in the southeastern coastal region, which encompasses the port cities of Busan, Masan, Yosu, Jinhae, Ulsan, and Pohang. Census figures show that Ulsan's population increased eighteenfold, growing from 30,000 to 551,300 inhabitants between 1960 and 1985. With the exception of Yosu, all of these cities are in South Gyeongsang Province, a region that has been an especially favored recipient of government development projects. By comparison, the population of Gwangju, capital of South Jeolla Province, increased less than threefold between 1960 and 1985, growing from 315,000 to 906,129 inhabitants. Rapid urban growth has brought familiar problems to developed and developing countries alike. The construction of large numbers of high-rise apartment complexes in Seoul and other large cities alleviated housing shortages to some extent. But it also imposed hardship on the tens of thousands of people who were obliged to relocate from their old neighborhoods because they could not afford the rents in the new buildings. In the late 1980s, squatter areas consisting of one-story shacks still existed in some parts of Seoul. Housing for all but the wealthiest was generally cramped. The concentration of factories in urban areas, the rapid growth of motorized traffic, and the widespread use of coal for heating during the severe winter months caused dangerous levels of air and water pollution, issues that still persist today even after years of environmentally friendly policies. In 2016,