4. Migration and Human Mobility
This guide explains why people move, how migration systems and policies shape movement, and how migration affects origin, transit, and destination regions.
Core concepts: and
changes where people live and connects places through economic, social, cultural, political, and environmental relationships. It usually involves an intended change of residence, while broader movement can also be temporary or repetitive.
may occur within a country or across an international boundary. includes as well as commuting, seasonal movement, circular movement, and other temporary forms of movement.
Types and components of a system
A system connects several kinds of places and relationships:
Origin regions are places where migrants begin their journeys.
Transit regions are places through which migrants travel.
Destination regions are places where migrants settle or work.
Networks include family members, friends, employers, recruitment agencies, transportation routes, and communication technologies.
A stream is movement from a common origin to a common destination. A counterstream moves in the opposite direction. may also occur in steps, such as movement from a village to a regional town, then to a national capital, and later to an international destination.
In 2024, approximately 304 million people lived in a country different from the country where they were born. This represented about 3.7 percent of the world’s population. Even though the absolute number of international migrants has nearly doubled since 1990, most people still live in their country of birth, and remains more common than . Nearly half of international migrants live within their region of origin, demonstrating that is often regional rather than truly global.
Takeaway: is one form of , and its scale must be understood through the connections among origins, transit places, destinations, and networks.
Historical patterns of
Human movement has shaped societies throughout history. Environmental change, technological innovation, warfare, economic opportunity, political expansion, and social pressures have all contributed to .
Early movement, agriculture, and empire
The initial peopling of the world involved movement across continents over thousands of years. Later, agriculture, pastoralism, trade, and states created new patterns of movement. Nomadic pastoralists moved seasonally with livestock, while traders and settlers established routes linking distant cultural regions.
Empires generated large-scale movement by relocating soldiers, administrators, merchants, enslaved people, and settlers. These movements spread languages, religions, technologies, crops, and political institutions, while also displacing existing populations.
Colonialism and forced
European colonial expansion created extensive voluntary and involuntary systems. Millions of Africans were forcibly transported across the Atlantic through the transatlantic slave trade and compelled to work in plantations, mines, households, and other economic systems in the Americas. This forced permanently altered the demographic and cultural landscapes of Africa, the Caribbean, North America, and South America.
After the abolition of slavery in many regions, colonial labor systems recruited contract workers from India, China, and other parts of Asia for plantations, mines, railroads, and construction. These movements helped form diasporas, or communities living outside an ancestral homeland while maintaining cultural, family, or economic ties to it.
Industrialization and mass
During the nineteenth and early twentieth centuries, industrialization, improved transportation, population growth, land shortages, famine, and political or religious persecution encouraged large-scale . Steamships and railroads reduced travel time and costs, making long-distance movement more feasible.
Nearly 12 million immigrants arrived in the United States between 1870 and 1900. Some were attracted by economic opportunities, while others were pushed by crop failures, famine, job and land shortages, high taxes, and persecution. Chinese to the United States increased during the California Gold Rush and later faced federal exclusion in 1882.
policy shaped these flows. The United States national-origins quota system of the 1920s favored some European populations over others. Later changes placed greater emphasis on family reunification and occupational skills, showing how governments use policy to make selective.
Postwar and contemporary movement
After World War II, expanded through decolonization, labor recruitment, movements, family reunification, education, and globalization. Contemporary includes labor , international education, family , urbanization, seasonal agricultural work, retirement , and . Transportation and digital communication also make it easier for migrants to maintain transnational connections with both origin and destination regions.
Takeaway: is not a new phenomenon. Its forms and directions change as technology, economic systems, political power, and environmental conditions change.
Why people move: Push and pull factors
decisions usually reflect a combination of conditions at the origin, attractions at the destination, and barriers or opportunities encountered along the way.
The identifies common factors:
Push factors include unemployment, low wages, political repression, persecution, war, violence, crime, natural hazards, environmental degradation, limited education or health care, land shortages, resource scarcity, discrimination, and social exclusion.
Pull factors include higher wages, more jobs, political freedom, personal security, safety, stability, better environmental conditions, stronger schools and medical services, access to land or housing, and family or community acceptance.
For example, a person may leave because of unemployment but choose a particular destination because a relative already lives there. This illustrates the importance of social networks as well as economic conditions.
Opportunities, obstacles, and perceived benefits
An intervening opportunity is an attractive option encountered before the intended destination. A person planning to migrate to a distant city may instead stop in a closer town if it offers employment, education, family support, or safety.
An intervening obstacle is a barrier that makes the intended movement more difficult. Examples include a border, visa restriction, high travel cost, dangerous route, language barrier, or lack of legal documents.
Place utility refers to the perceived benefits of a destination compared with the costs and risks of reaching it. People often have incomplete information and therefore rely on personal networks, social media, recruiters, news, and the experiences of previous migrants.
Economic conditions matter, but is not simply movement from poor places to rich places. Many people lack the resources to migrate internationally, and some migrants move between countries with similar income levels. Conflict, family relationships, education, climate hazards, historical ties, and government policies also shape decisions.
Takeaway: results from interacting push factors, pull factors, opportunities, obstacles, perceived destination benefits, and available information.
Who migrates? Selectivity and migrant characteristics
Migrants are not a random sample of the population. is selective because the likelihood of moving varies with age, sex, education, income, occupation, family status, ethnicity, legal status, transportation, and access to information.
Age and life course
Young adults are often more likely to migrate in search of employment, education, independence, or marriage. Older adults may move for retirement, health care, or family support. Families with children may be less mobile in the short term because moving involves schooling, housing, and child-care decisions.
Education, skills, and income
People with higher education or specialized skills may have more opportunities to obtain visas and employment abroad. This can produce , the loss of highly educated workers from an origin region. Destination countries may gain doctors, engineers, teachers, and other professionals, while origin regions may lose important skills.
can also create brain circulation when migrants return, collaborate across borders, or transfer knowledge and investment. Low-income people may have strong reasons to migrate but lack the money, documents, or networks required to do so. International migrants are therefore often selected from the middle or upper portions of the origin population rather than from the poorest households.
Gender and family status
Gender patterns vary by region, occupation, and historical period. Men have dominated some forms of long-distance labor , while women have played major roles in domestic work, health care, manufacturing, education, family , and movements. Policies favoring family reunification can produce chain , in which migrants join relatives who migrated earlier.
Policy selectivity
States also select migrants through their rules. Governments may favor particular skills, education levels, family relationships, investment capacity, or humanitarian needs. Recruitment systems may admit temporary agricultural workers, international students, or health professionals while restricting other groups.
Takeaway: Who migrates depends not only on personal motivation but also on life stage, resources, skills, family networks, and access to legal pathways.
and protection
Forced movement occurs when remaining at home is severely constrained or unsafe. may result from persecution, armed conflict, violence, human-rights violations, disasters, or other events that seriously disturb public order.
Important legal and geographic categories
An has been forced to flee but remains within the borders of the person’s own country.
A is outside the country of nationality or habitual residence and cannot safely return because of persecution or another legally recognized threat.
An has requested international protection, but the claim to status has not yet been finally decided.
A is not recognized as a national by any state under its law.
The key distinction between a and an IDP is whether an international border has been crossed. People who remain inside their country may receive help from national authorities and international agencies, but they generally do not receive the same international legal protection as refugees.
At the end of 2024, UNHCR estimated that 123.2 million people worldwide were forcibly displaced because of persecution, conflict, violence, human-rights violations, or events seriously disturbing public order. More than one-third of the world’s forcibly displaced people were from Sudan, Syria, Afghanistan, or Ukraine. Most refugees remain relatively close to their countries of origin. In 2025, approximately 65 percent of refugees and other people needing international protection lived in neighboring countries, while low- and middle-income countries hosted about 68 percent of that population.
Durable solutions and settlement pressures
may be temporary, protracted, or repeated. Three commonly discussed durable solutions are:
Voluntary repatriation: returning safely and voluntarily to the country of origin.
Local integration: establishing a permanent life in the country of asylum.
Resettlement: transferring to a third country that agrees to admit and protect the .
camps and informal settlements may grow rapidly, placing pressure on water, land, food supplies, sanitation, schools, and health services. Host communities may experience challenges as well as benefits, including new labor, entrepreneurship, cultural exchange, and international aid.
Environmental hazards can contribute to displacement, but their effects are not automatic. Drought, flooding, storms, sea-level rise, and land degradation may reduce livelihoods or make places unsafe. Income, government policy, conflict, infrastructure, social networks, and the ability to move influence how people respond. Many people affected by environmental stress move internally, move temporarily, or do not move at all.
Takeaway: is shaped by both immediate threats and the legal geography of movement, especially whether people cross an international border.
policy and governance
policy consists of the laws, regulations, institutions, and agreements governing entry, residence, employment, citizenship, asylum, border control, deportation, family reunification, and integration.
Governments may use policy to:
Regulate who may enter and how long they may stay.
Recruit workers in occupations with labor shortages.
Protect national security and public order.
Provide asylum or temporary protection.
Reunite families.
Encourage or restrict permanent settlement.
Manage and human trafficking.
Support integration through language, education, employment, and health programs.
Facilitate remittances and development in origin countries.
occurs through an authorized legal pathway. occurs when a person lacks required authorization or violates entry or residence conditions. Irregular status may result from unauthorized entry, visa overstaying, or loss of legal status after an application is denied. It is an administrative condition, not a description of a person’s character.
The Global Compact for Safe, Orderly and , adopted by United Nations member states in 2018, is a non-legally binding framework containing 23 objectives for cooperation on . It emphasizes state sovereignty, human rights, responsibility-sharing, and safer, more predictable governance.
Unintended effects and cooperation
Strict restrictions may reduce legal opportunities without eliminating the reasons people move. Migrants may then rely on smugglers, take more dangerous routes, or remain in irregular status. Expanding safe and regular pathways can reduce risk, improve labor-market matching, and make movement easier to monitor.
Governments also have responsibilities to manage borders, protect residents, enforce labor standards, and allocate public resources. Effective governance therefore requires cooperation among origin, transit, and destination countries. Policies should distinguish among labor migrants, family migrants, refugees, asylum-seekers, students, victims of trafficking, and people displaced by disasters. Treating all mobile populations as one category can produce inaccurate statistics and inappropriate policies.
Takeaway: governance must balance border management, human rights, labor needs, protection obligations, integration, and cooperation across countries.