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Undocumented migration: an overview

Migration A–Z


  1. Colleen Thouez

Published Online: 4 FEB 2013

DOI: 10.1002/9781444351071.wbeghm553

The Encyclopedia of Global Human Migration

The Encyclopedia of Global Human Migration

How to Cite

Thouez, C. 2013. Undocumented migration: an overview. The Encyclopedia of Global Human Migration. .

Publication History

  1. Published Online: 4 FEB 2013


Undocumented migration, irregular migration, or “illegal” migration can be defined as movement that takes place outside the regulatory norms of the origin, transit, or destination country (IOM 2011). Globally, the International Labour Organization (ILO) estimates the number of undocumented migrants to be 15–30 million though this range is undoubtedly at the low end (ILO 2004). In the United States, it was estimated that there were 11 million undocumented migrants in 2008, down from 12.5 million in 2007 (Center for Immigration Studies). From 2000 to 2005, an estimated annual average of 500,000 undocumented migrants entered the United States, more than the average number of legal immigrants (Passel & Taylor 2010). There is very little available data disaggregated by sex and by age (IOM/CMS 2010a). As in other sub-areas related to migration, it is useful to distinguish between stocks and flows of migrants.


  • immigration;
  • labor;
  • labor supply;
  • poverty;
  • social justice;
  • political economy