The global volume of immigration is high in absolute terms, but low in relative terms. The UN estimated 190 million international migrants in 2005, about 3% of global population. The other 97% still live in the state in which they were born, or its successor state.

The modern idea of immigration is related to the development of nation-states and nationality law. Citizenship of a nation-state confers an inalienable right of residence in that state, but residence of immigrants is subject to conditions set by immigration law. The nation-state made immigration a political issue: by definition it is the homeland of a nation defined by shared ethnicity and/or culture, and in most cases immigrants have a different ethnicity and culture. This has led to social tensions, xenophobia, and conflicts about national identity, in many developed countries.

According to the Report of the Secretary-General on International Migration and Development, most international migrants are in the high-income developed countries, 91 million in 2005.  Low and lower-middle income countries have 51 million international migrants. Migration flows are not solely from poor to rich, though; a third of international migrants move from one developing country to another. The absolute number of international migrants is highest in the United States at 39 million.

Immigration is often highly politicized, and in some countries, a major political issue. The main arguments cited in support of immigration are economic arguments, usually related to labor supply, and cultural arguments appealing to the value of cultural diversity. Some groups also support immigration as a device to boost small population numbers, like in New Zealand, or, like in Europe, to reverse demographic aging trends. The main anti-immigration themes are xenophobia, economic issues (costs of immigration, and competition in the labor market), environmental issues (impact of population growth), and the impact on the national identity and nature of the nation-state itself.

Support for fully open borders is limited to a minority. Some free-market libertarians believe that a free global labor market with no restrictions on immigration would, in the long run, boost global prosperity. There are also groups which oppose border controls on idealistic and humanitarian grounds - believing that people from poor countries should be allowed to enter rich countries, to benefit from their higher standards of living.

• 03/10/2007 11:32
  • 03/10/2007 11:32