Discussions about migration typically start from the perspective of flows from developing countries into the rich countries of Europe, North America and Australasia. Yet most movement in the world does not take place between developing and developed countries; it does not even take place between countries. The overwhelming majority of people who move do so inside their own country. Using a conservative definition, we estimate that approximately 740 million people are internal migrants—almost four times as many as those who have moved internationally. Among people who have moved across national borders, just over a third moved from a developing to a developed country—fewer than 70 million people. Most of the world’s 200 million international migrants moved from one developing country to another or between developed countries (map 1).
Most migrants, internal and international, reap gains in the form of higher incomes, better access to education and health, and improved prospects for their children. Surveys of migrants report that most are happy in their destination, despite the range of adjustments and obstacles typically involved in moving. Once established, migrants are often more likely than local residents to join unions or religious and other groups. Yet there are trade-offs and the gains from mobility are unequally distributed.
People displaced by insecurity and conflict face special challenges. There are an estimated 14 million refugees living outside their country of citizenship, representing about 7 percent of the world’s migrants. Most remain near the country they fled, typically living in camps until conditions at home allow their return, but around half a million per year travel to developed countries and seek asylum there. A much larger number, some 26 million, have been internally displaced. They have crossed no frontiers, but may face special difficulties away from home in a country riven by conflict or racked by natural disasters. Another vulnerable group consists of people—mainly young women—who have been trafficked. Often duped with promises of a better life, their movement is not one of free will but of duress, sometimes accompanied by violence and sexual abuse.
In general, however, people move of their own volition, to better-off places. More than three quarters of international migrants go to a country with a higher level of human development than their country of origin. Yet, they are significantly constrained, both by policies that impose barriers to entry and by the resources they have available to enable their move. People in poor countries are the least mobile: for example, fewer than 1 percent of Africans have moved to Europe. Indeed, history and contemporary evidence suggest that development and migration go hand in hand: the median emigration rate in a country with low human development is below 4 percent, compared to more than 8 percent from countries with high levels of human development.