Historical patterns and recurring opposition
Mexicans occupy the first place among the national groups with the largest number of immigrants. It is estimated that there are approximately 11 million and that just over half are undocumented. Such figures reflect the present of a historical pattern of migration to the north that is almost a century and a half old. Unlike other cases, Mexican migration has been continuous since the end of the 19th century, when US employers began the massive recruitment of Mexicans to work in the railroads, agriculture, mines, and industry. The demand for labor has persisted and, at times like World War II, increased considerably.
During much of this period the flows were circular. This pattern has changed significantly as the militarization of the border with Mexico has increased. Another possibly unexpected impact of such a migration/security policy is that migrants have chosen to bring their relatives to the United States rather than continue the old tradition of annual returns to Mexico. Consequently, there has been an increase in the number of undocumented Mexicans. Opposition to Mexican immigration is not unanimous nor is it new. In some historical periods, Mexicans have been benefited by migratory policies (for example, the Chinese Exclusion Law of 1882 led to the massive importation of Mexicans, the Bracero Program offered 4. 5 million temporary work contracts) and in others they have become the favorite target of political/social forces (Great Depression of 1929, present). These positions have co-existed and the relevance of each one has been the result of the correlation of forces at that time.