Since the beginning of the twentieth century, the United States has experienced several waves of Mexican immigration. The latest and most voluminous one started in the early 1970s and more than quintupled the Mexican-origin population from 4.5 million to 25.5 million in 2005 (Camarillo 510). Mexican migrants do not only represent the largest group of legal permanent residents (green card holders), they also constitute the majority among illegal aliens. These illegal Mexican immigrants predominantly entered in the past ten years.

The swift increase of the unauthorized Mexican population originated, flourished, and was molded by outdated US immigration policies and by deliberate maintenance of legal loopholes giving US employers the opportunity of worker exploitation. Moreover, the rapid growth was induced by diametrical economic developments in the US and Mexico creating an economy that works both ways. The United States is able to satisfy labor demands in various industries such as construction, manufacturing, and service, while Mexicans are offered an opportunity to earn more money and support their families with higher remittances. This labor and monetary exchange turned the availability of cheap Mexican labor in the US and US foreign direct investment into Mexico into central aspects of the economic development in both countries.