What does Mexico's prominence in the U.S. migration system mean for U.S. immigration policy? On one hand, it means that U.S. immigration policy, to varying degrees, primarily affects Mexicans and Mexico. Today's Mexico-U.S. migration flows and the Mexico-born population in the United States are the product of previous immigration policy decisions, as well as of the long and complex history of the U.S. and Mexican economies, labor markets, and demographics. On the other hand, it also means that Mexico remains at the center of today's immigration debate, even if sometimes only implicitly. Recognizing Mexico's status within the U.S. migration system focuses attention on how the U.S. immigration debate affects Mexico, and on how Mexico may affect certain migration outcomes. This report begins with an overview of Mexico-U.S. migration flows, and reviews the history of migration policies in both countries. The last section of the report discusses four major issues in the U.S. immigration debate: migration control and border security, the lawful permanent resident (LPR) visa system, temporary worker programs, and potential legalization programs for certain unauthorized aliens. Does Mexico support U.S. immigration policy goals? Thus, legislative and administrative action during the last decade mainly has focused on new enforcement measures at the U.S.-Mexican border and within the United States; and a record number of unauthorized aliens have been removed in each year since 2003, with Mexicans accounting for almost three-quarters of all removals (see " Immigration Enforcement and Border Security "). History of Mexico-U.S. Migration and Policies

This section describes how social, economic, and demographic factors in Mexico and the United States along with migration-related policies in both countries have produced four phases in the regional migration system: limited seasonal flows prior to World War II, the Bracero temporary worker program from 1942 to 1964, the emergence of a predominantly illegal system from 1965 through the 1980s, and the consolidation of that system along with increased family-based immigration since the 1990s. Congress examined the issue for 15 years and then passed the Immigration Reform and Control Act of 1986 (IRCA, P.L. At the same time, immigration reforms sought to reduce low-skilled employment-based inflows. Beginning in the late 1990s, however, increasing migrant deaths along the U.S.-Mexico border, the precarious situation of unauthorized Mexican migrants in the United States, and attention to human rights abuses of Central Americans in Mexico led the Mexican government to take a more active approach to migration issues, including by reforming its own migration policy and by engaging with the United States about U.S. immigration policy. On average, the Mexican born in the United States are more likely than other foreign born to be unauthorized; and compared to other foreign-born and native-born populations in the United States, Mexicans are younger, have lower education levels, are more likely to work in lower-skilled occupations, and have lower measures of economic well-being. Mexico's status as the largest source of U.S. migrants and as a continental neighbor means that many U.S. policies primarily affect Mexicans. Under the agreement, announced on September 6, 2001, the two presidents outlined a bilateral approach to migration reform that would combine a new Mexico-U.S. guest worker program, legalization for most unauthorized Mexican migrants in the United States, enhanced border enforcement including steps by Mexico to discourage illegal outflows, and increased U.S. investment to create alternatives to emigration in Mexican migrant-sending communities. Immigration Enforcement and Border Security

Immigration enforcement and border security are at the heart of the immigration debate, including questions about how to prevent or deter illegal migration across the U.S.-Mexican border and the removal of unauthorized migrants and certain other aliens from within the United States. Mexico's Role in Migration Control

Given the large number of unauthorized Mexicans in the United States, some people believe that Mexico bears some responsibility for illegal flows and should play a greater role in migration control. One way to increase Mexico's role in migration enforcement may be for Congress to consider additional investments in these programs. Long waiting lists for people with approved petitions divide families, and may be a factor in the decision by some family members to migrate illegally. Mexicans were exempted from certain grounds for inadmissibility during World War I; Mexicans (and other Western Hemisphere immigrants) were not subject to numeric limits like Europeans and other Eastern Hemisphere immigrants after 1921; and Mexicans had privileged status under the Bracero program. Reducing Unauthorized Emigration from Mexico

Poverty and a lack of economic opportunities have been major drivers of Mexico-U.S. migration, and scholars have long suggested that fostering development in Mexico could reduce unauthorized migration flows. The size of the Mexican population in the United States, its demographic characteristics, and its increasing dispersion to new U.S. destinations all place Mexico at the center of the U.S. immigration debate; and the proportion of Mexicans who migrate to the United States also places migration issues at the center of the bilateral relationship. Many of the core issues in the U.S. immigration debate—including efforts to strengthen migration control and border security, possible reforms to the lawful permanent resident and nonimmigrant visa systems, and proposals to legalize certain unauthorized migrants—have important implications for both countries. In the long run, the future of the U.S.-Mexican migration relationship depends in great part on economic and demographic trends in both countries, and their impact on regional migration flows.
History and geography have given Mexico a unique status in the U.S. immigration system, and have made the Mexico-U.S. migration flow the largest in the world. Mexicans are the largest group of U.S. migrants across most types of immigration statuses—a fact that may have important implications for how Congress makes U.S. immigration policy. This report reviews the history of immigration policy and migration flows between the countries and the demographics of Mexicans within the United States. It also analyzes contemporary issues in U.S. immigration policy and the impact Mexico may have on U.S. immigration outcomes.
The U.S.-Mexican migration system has passed through four main phases since the early 20th century. Migration flows were limited and mainly short-term prior to the 1920s, and Mexicans were exempted from certain immigration restrictions and admitted as the first U.S. guest workers during World War I. The bilateral "Bracero" temporary worker program marked a second phase, with 4.6 million temporary visas issued to Mexican workers between 1942 and 1964. With the end of the Bracero program and other immigration reforms in 1965, along with social and economic changes in the United States and Mexico, the third stage was marked by growing illegal inflows, eventually leading Congress to pass the Immigration Reform and Control Act of 1986. Finally, despite a series of additional enforcement measures, the Mexican population in the United States doubled during each decade since 1970, with unauthorized migrants accounting for a majority of the growth, followed by legal family-based immigration.
Today, the Mexico-born population in the United States stands at about 11.7 million people. Compared to other migrants, the Mexican born in the United States are more likely to be unauthorized, be younger, have lower education levels, work in lower-skilled occupations, and have lower measures of economic well-being. In contrast with earlier periods and virtually all other migrants, Mexicans are now dispersed throughout all 50 U.S. states.
Given the size of the Mexico-born population in the United States and the 2,000-mile border shared between the two countries, Mexicans and Mexico are uniquely affected by U.S. immigration policies. Mexicans are the largest group of aliens subject to U.S. immigration control and border security policies, the largest group of lawful immigrants within permanent and temporary visa categories, and the majority of unauthorized migrants within the United States.
On one hand, Mexico's prominence in the U.S. migration system means that U.S. immigration policy, to varying degrees, primarily affects Mexicans and Mexico. Today's Mexico-U.S. migration flows and the Mexico-born population in the United States are the product of previous immigration policy decisions, as well as of the long and complex history of the U.S. and Mexican economies, labor markets, and demographics. On the other hand, Mexico also remains at the center of today's immigration debate, though often only implicitly. Recognizing Mexico's status within the U.S. migration system focuses attention on how the U.S. immigration debate affects Mexico, and on how Mexico may affect certain migration outcomes.
Mexico's role in the U.S. immigration system, along with the importance of the bilateral relationship to both countries, creates a number of opportunities, and challenges, as Congress weighs changes to U.S. immigration policy. First, Mexico already plays a key role in U.S. immigration enforcement and border security. The United States and Mexico share information about transnational threats, Mexico combats illegal migration by third country nationals, and Mexico supports certain U.S. enforcement efforts related to the repatriation of Mexican nationals. This report explores possibilities for additional bilateralism in these areas, including strategies to reduce recidivism among illegal migrants and to better manage U.S.-Mexican ports of entry.
Second, with respect to lawful permanent immigration, Mexico benefits from rules that favor family-based flows, but still dominates the waiting lists of people with approved immigration petitions for whom visas have not yet been made available. The analysis here focuses attention on recent proposals to reduce visa backlogs and on other reforms that could affect the number of immigrant visas for Mexico.
Third, Mexico dominates temporary visa categories for low-skilled workers, and an increasing number of Mexicans could also qualify for high-skilled worker visas. The report reviews previous experience with Mexico-specific temporary worker programs, which offer mixed lessons about managing flows this way.
Additional policy considerations concern potential legalization proposals and efforts to reduce unauthorized emigration from Mexico. Given the large number of unauthorized Mexican migrants in the United States, Mexico could play a role in a potential legalization program, including by providing information to verify migrants' identities and by facilitating proposed "touch-back" requirements. Finally, in the long run, economic development and employment creation in Mexico are widely viewed as being among the best tools to reduce unauthorized emigration. While demographic and economic trends in Mexico likely have already contributed to reduced illegal outflows, the relationship between international trade and financial flows, U.S. economic assistance, and economic opportunities in Mexico may represent promising areas for policies to reduce illegal migration in the future.
This report supplements other CRS research on Mexico (such as CRS Report RL32724, Mexico: Issues for Congress; and CRS Report R41349, U.S.-Mexican Security Cooperation: The Mérida Initiative and Beyond ) and on immigration (such as CRS Report R42036, Immigration Legislation and Issues in the 112th Congress; and CRS Report R42138, Border Security: Immigration Enforcement Between Ports of Entry).