Japanese nationals living in other countries totaled more than 600,000 in the 1990s, including some 250,000 in the United States and over 100,000 in Brazil. More than one million Japanese have emigrated since 1880; about 70% of them arrived on the US mainland and in Hawaii during the decades prior to World War II. Emigration continued after the war, encouraged by government policy as a way of relieving population pressure. By the mid-1960s, emigration had considerably decreased, as economic opportunities and living standards in Japan improved. Since the early 1970s, however, the number of emigrants has again risen sharply, reaching 82,619 in 1992 (compared to 12,445 in 1975 and 34,492 in 1985).
Immigration to Japan is generally small-scale, although in recent years the illegal entry of workers from neighboring countries has come to be regarded as a problem. Since 1975, 10,000 Indo-Chinese refugees have settled in Japan. In the mid-1990s there were 1,300,000 registered aliens, of which 690,000 were Koreans. The number of illegal aliens may be even higher. Some 150,000 Chinese constituted the second-largest group. Nearly 42,000 foreigners entered as permanent residents per year. Because citizenship is based on nationality of parent rather than place of birth, registered aliens may have spent their entire lives in Japan. In 1999 the net emigration rate was 0.34 migrants per 1,000 population.
Internal migration, providing a steady exodus of people from farm and mountain communities to the cities and suburbs, has been accelerating since 1952. Most such migrants flocked to the three major population centers—the Tokyo, Osaka, and Nagoya metropolitan areas. As pollution and congestion in these areas increased, the government instituted programs to decentralize industry by directing new growth to smaller cities of the north and west, and also began efforts to improve rural living conditions and employment opportunities.