Human migration

• 1. Introduction

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  Human migration is the movement of people from one place to another with the intention of settling, permanently or temporarily, in a new location. In 1970, roughly 84 million people lived outside their place of origin, about 2.3% of the world's population. By 2020, that figure had climbed to more than 280 million, or 3.6%. Yet behind those numbers sits a paradox. The form of migration most people picture, the crossing of an international border, is not the dominant one. Internal migration, the movement of people within a single country, is the larger story globally. Who counts as a migrant, who counts as a refugee, and who counts as an asylum seeker? Why do people leave at all, and what do they carry back to the places they left? And why, across five decades of upheaval, has the share of migrants in the world stayed so stubbornly close to 3 percent?

• 2. Three Names For Leaving

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  The UNHCR defines refugees as "persons forced to flee their country because of violence or persecution." Their reasons usually involve war within the source country or other forms of oppression, whether from a government or non-governmental sources. Because such people must relocate as fast as possible, they may move without documentation at all.

  Migrants, by contrast, are traditionally described as persons who change their country of residence for general reasons, such as better job opportunities or healthcare needs. This is the most widely understood of the three terms. Anyone who changes their geographical location permanently becomes a migrant.

  Asylum seekers occupy the space between. They leave their country unwillingly, yet not under the extreme pressure of war or death threats. Their motivation might be an unstable economic or political situation or high rates of crime, a flight from the degradation of their quality of life. If an asylum seeker's formal request for shelter is approved by a host country, their legal classification changes to that of a refugee. Those who flee but remain inside their own country carry a different label still: internally displaced persons.

• 3. The Shape Of Global Flows

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  In 2013-38% of all migrants had moved from one developing country to another, a pattern known as South-South migration. Another 23% had moved between high-income OECD countries, North-North migration. The familiar image of the poor traveling to the rich captures only part of the picture. The United Nations Population Fund noted that between 2000 and 2013, the migrant population in developing regions grew at an average annual rate of 2.3%, slightly faster than the 2.1% in developed regions.

  Almost half of today's migrants are women, one of the most significant shifts in migration patterns over the last half-century. Female migration has long been viewed as an association with family rather than independent movement, but emerging studies argue the reasons are complex and manifold.

  As of 2024, the top ten destinations for international migrants began with the United States, Germany, Saudi Arabia, the Russian Federation, and the United Kingdom. The largest countries of origin were India, Mexico, the Russian Federation, China, and the Syrian Arab Republic. Concentration is visible at the city scale too. The New York metropolitan area holds the largest ethnic Chinese population outside Asia, an estimated 893,697 uniracial individuals as of 2017, sustaining thriving Chinatowns across Queens, Manhattan, and Brooklyn.

• 4. Pushed And Pulled

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  The government of Armenia periodically offers incentives to people willing to move into villages close to the border with Azerbaijan. People avoid living there because of security concerns rooted in tension and hostility, so the state must actively pull settlers toward a place its own population would push away from. The example captures a wider logic that demographers use to explain voluntary movement.

  "Push" factors are the negative aspects of a country of origin, things like war, poor quality of life, lack of jobs, excessive pollution, hunger, drought, or natural disasters. "Pull" factors are the positive aspects of a destination that attract people seeking a better life. Demographer Everett S. Lee built his model around exactly this split. His list of push factors ran from conscription and famine to political persecution, loss of wealth, and even poor chances of marrying. His pull factors included job opportunities, better medical care, attractive climates, education, family links, and security.

  The distinction between voluntary and forced migration is harder to draw than it looks. The motivators are often correlated, which makes the line partly subjective. By the end of 2018, an estimated 67.2 million people were forced migrants: 25.9 million refugees displaced from their countries, and 41.3 million internally displaced within them. In 2022 alone, 6 million Ukrainian people fled their country.

• 5. The Money That Follows

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  In 2015, migrants made up 3.3% of the world's population but contributed 9.4% of global GDP. Their economic value is recognized at the level of individual firms as well. A 2021 survey by the Boston Consulting Group found that 72% of more than 850 executives across several countries believed migration benefited their countries, and 45% considered a globally diverse workforce a strategic advantage. The Centre for Global Development has estimated that opening all borders could add $78 trillion to world GDP.

  Remittances, the funds migrant workers send back home, form a substantial part of some national economies. For the top recipient countries, these transfers can reach tens of billions of US dollars, and in some cases they make up a meaningful percentage of the home country's entire GDP. The flows are large enough that the United Nations built them into its development goals. Sustainable Development Goal 10 targets cutting the transaction cost of migrant remittances to less than 3% by 2030.

  Money is only one part of what migrants carry across borders. They also contribute to food and cuisine, sport, music, art, and the realm of ideas and beliefs, alongside civic and political participation in their host societies.

• 6. Theories Of The Move

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  Neoclassical economic theory holds that the main reason for labour migration is the wage difference between two geographic locations. Areas short on labour but rich in capital pay high relative wages; areas with abundant labour and scarce capital pay low ones. Labour flows from the low-wage areas toward the high-wage ones.

  Dual labour market theory points instead at the destination. It assumes developed economies split into two segments: a primary market needing high-skilled workers, and a labour-intensive secondary market needing low-skilled ones. Native workers avoid the lowest rung because it offers no mobility, so the pull for migrant labour comes from that unfilled need.

  The new economics of labor migration argues that individual incentives are not enough to explain why people move. It looks at the household, where migration can act as a form of risk aversion. A family with insufficient income sends a member abroad, and the remittances that flow back become the extra capital it needs.

  World-systems theory zooms out to the global scale, arguing that trade which causes economic decline in one country can create an incentive to migrate toward a more vibrant economy. Stranger still is osmosis theory, which studies migration through a biophysical analogy. Countries become animal cells, borders become semipermeable membranes, and humans become ions of water moving from regions of low migration pressure to regions of high pressure.

• 7. Who Governs Movement

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  International migration is, by its nature, a transnational issue, touching the country of origin, the destination, and the so-called transit states in between. Paradoxically, the bulk of migration governance has stayed with individual states, made at the national level and tied closely to state sovereignty. States keep the power to decide on the entry and stay of non-nationals because migration affects the defining elements of a state itself.

  A handful of widely ratified treaties sit above the national level. The 1966 International Covenant on Civil and Political Rights and the 1951 Convention Relating to the Status of Refugees are two significant examples. Others have struggled for acceptance, such as the International Convention on the Protection of the Rights of All Migrant Workers and Members of Their Families, which still counts no traditional destination country among its parties.

  The Global Compact for Safe, Orderly and Regular Migration marked another milestone, the first internationally negotiated statement of objectives for migration governance. Though not legally binding, it was adopted by consensus in December 2018 at a United Nations conference attended by more than 150 Member States, then carried in the General Assembly by a vote of 152 to 5 with 12 abstentions. Governance also has a long shadow. Colonialism globalized systems of migration, and after decolonization, the migration ties between former colonies and former metropoles have continued into the present day.