Poverty, injustice and armed conflict displace millions of people across the globe. In the past 30 years, the number of international migrants has more than doubled, to an estimated 191 million worldwide. (1) These include economic migrants compelled to move to provide for their families, refugees and internally displaced persons fleeing persecution, and victims of human trafficking. The vast majority are economic migrants who have few options to remain in their countries of origin. There are roughly 30 to 40 million undocumented migrants worldwide, comprising around 15–20 percent of the world's migrant population. An understanding of the forces that favor or necessitate migration is necessary if we are to maximize benefits and minimize harm to migrants, their families, and sending and receiving nations.

Around 550 million people with jobs are living on less than $1 a day, while almost half of the world’s 2.8 billion workers earn less than $2 a day. (2)

Latin American immigrants working in the United States sent home $45 billion – about 10 percent of their earnings – in remittances in 2006. (3)

The ratio of the average income of the five richest countries to the 5-10 poorest was 9 to 1 in terms of purchasing power in 1900; it is 100 to 1 today. (4)

In the absence of a livable wage, access to credit, insurance or social welfare benefits, the value of migration is greater than its hardship or potential for exploitation.

The average per capita income in Haiti is $400 per year. In the United States, an undocumented, unskilled day laborer can earn that much in one week. (5)

The southern hemisphere has large labor forces coupled with limited demand and capital, while the northern hemisphere has limited labor forces coupled with large demand and capital.

“The global labor force will rise from 3.0 to 3.4 billion in the period of 2001 to 2010 (40 million yearly). Some 38 million of that annual growth will come from developing countries, and only two million from high-income countries.” (6)

Aging populations and low fertility rates in industrialized countries have resulted in a substantial decline in “replacement workers” entering the workforce, while also creating greater demand for service-sector jobs and low-skill employment. Developed countries have come to rely on migrants to fill their labor needs as workers and as taxed wage-earners.

Special thanks to the staff of Catholic Relief Services for their help in preparing this piece. CRS, founded in 1943, is the official international relief and development agency of the U.S. Catholic community. Headquartered in Baltimore, CRS serves 80 million people in nearly 100 countries on five continents.

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(1) Global Commission on International Migration, “Migration in an Interconnected World: New Directions for Action,” (2005) p. 11.
(2) Ibid., 11.
(3) Council of Economic Advisors, “2007 Economic Report of the President,” 191.
(4) Nancy Birdsall, “Rich Country Aging: Poor Country Risks,” to the Federal Reserve Bank of Kansas City Symposium, August 2004.
(5) Reuters Factbox, February 5, 2006.
(6) Global Commission Report, 14.