It is impossible to say exactly how many undocumented immigrants are living in the United States precisely because no authority documents their entry into the country. (This is one reason why researchers like myself prefer the term “undocumented immigrant” to “illegal immigrant”—see my article about how we should refer to people who migrate illegally.)
Researchers therefore use various techniques to make estimates (approximate calculations) of the size of the undocumented population. The best estimates that I am aware of come from the Pew Hispanic Center (PHC), a nonpartisan research institute based in Washington, DC. In a report published February 1, 2011, the PHC estimated that there were about 11.2 million undocumented immigrants living in the U.S. in March 2010. This is down from an estimated 12 million undocumented immigrants living in the U.S. in March 2007. A handful of factors explain the decrease in the undocumented population between 2007-2010, including: the economic downturn in the U.S., the growing intensity of drug cartel violence near the US-Mexico border, lower birthrates in Mexico, and stricter border enforcement by the United States.
To put all this in perspective, consider that undocumented immigrants make up about 3.6% of total US population.
Mexicans make up the largest share of the undocumented population, at about 6.7 to 7 million people, or 59% of the total.
Why do comparatively so many Mexicans migrate illegally?
Part of the explanation has to do with Mexico’s relative poverty and proximity. Mexico shares a 2000-mile land border with the United States. This border marks the largest income gap between any two neighboring countries in the world. The US-Mexico border is also something that meant much less in the past, and hundreds of thousands of Mexicans used to come and go between home and the US every year with relative ease until our immigration laws changed so dramatically in 1986. This long history as neighbors means that the border splits millions of Mexican and American families. As a result of the U.S-Mexico income disparity and our countries’ exceptional social, economic, and historical ties, a lot of Mexicans want to migrate to the US.
Another part of the explanation has to do with the fact that our immigration laws essentially treat Mexicans the same as just about any other nationality despite Mexico’s special status as a neighbor. That so many Mexicans compete with each other for such a small number of visas means that it’s virtually impossible for the typical Mexican immigrant to enter the country legally in his or her lifetime. With no way to enter legally, people make the difficult decision of migrating illegally.
In 2010, the US provided just under 180,000 visas to Mexicans for labor and family unification purposes. This figure is equivalent to just 2.7% the size of the undocumented Mexican population and 0.06% of total US population.
Other topics you might be interested in:
- You can read more about visas here.
- Read about the total number of immigrants living in the US and historical comparisons here.
- Do illegal immigrants pay taxes?