Pastor categorizes the last century (ending in the 1980s) as falling into several categories, with regard to immigration policy, which he also notes is open for debate, as it is usually done in public debates in Congress and between the executive branch and congress. While policy during this period may be categorized in many ways, a Latin American perspective suggests four useful divisions...: Defining Limits, 1875-1921; the Classical Special Relationship, 1921-1964; From Special Relationship to Global Policy, 1965-1978; and the Special Case -- Illegal Migration.

1984, p. 37)

The shift associated with immigration from, European sources to Latin America, and namely Mexico is well documented and determinant of many social issues, including those designated with the legal immigration sphere as well as those designated illegal, by virtue of the manner in which immigration is done. This was also a shift, in that there had been significant movements during and following the great depression, in the 1930s to suppress immigration from Mexico, relating to fears associated with mass unemployment and economic fear. After this period, restrictions were relaxed, especially as the Mexican and other Latin American nations economies have fluctuated in and out of livable circumstances for a growing population.

As the U.S. economy sank into depression, immigration again became an issue. In 1930 a concerted attempt was made to remove Mexico, the independent Caribbean, and the rest of Latin America from the quota-exempt category. The debate focused on illegal migrants from Mexico, who were alleged to be taking jobs at a time of rising unemployment.... Senator Henrik Shipstead of Minnesota posed the issue compellingly: "I would very much prefer to have it found possible not to put any of the nations of the Western Hemisphere on a quota basis, but in view of our unemployment situation, I do not see how we are going to avoid it." (Pastor, 1984, p. 41)

Though immigration...

Since this time immigration has seen a reduction in restrictions, for our close neighbors, such as Mexico, as population growth in Mexico and a flagging Mexican economy have created need for employment for Mexicans. Though the current debates in the popular media and the national government revolves around illegal immigration and the fear of resources being lost to undocumented workers, there is still a significant immigration pattern, of the legitimate kind from Mexico. (Dunn, 2001, p.7) (Borjas, 2001, p. 69) (Briggs, 1996, p. 371)
As immigration is a basic social situation in America, based on the real and perceived standard of living and opportunity levels in the U.S. there is no doubt that immigration will remain a strong social current in the nation. (Jonas, 1996, p.68) (Tichenor, 2002)