Mexico's president backs Bush

1917: U.S. Immigration Act mandates a literacy test for immigrants.

1918: Under pressure from farming groups, the INS commissioner waives the immigration act requirements for Mexican laborers.

1924: U.S. Border Patrol established.

1929: Amid Great Depression, U.S. deports thousands of Mexicans by enforcing laws that were previously waived. By 1932, 345,000 Mexicans were sent back to their homeland.

1942: The Bracero Treaty between the United States and Mexico establishes a guest worker program, partly to counter a labor shortage during World War II. An estimated 5 million Mexicans entered the country under the program.

1954: Amid growing anti-immigrant sentiment, the border patrol launches a massive roundup of Mexicans in the southwestern states, known as "Operation Wetback." Up to one million undocumented [illegal alien] Mexicans are sent back over the border in 1954, the peak year for the program.

1963: Congress allows Bracero program to expire under pressure from civil rights groups and unions concerned about the working conditions of migrant workers.

1965: The Immigration and Naturalization Act changes the criteria for immigration from national quotas to a system based on family reunification and job skills requirements.

1986: The Immigration Reform and Control Act offers an amnesty program for aliens in the country before 1982, imposes fines on employers who knowingly hire undocumented aliens and establishes a temporary resident category for agricultural workers.

1994: The North American Free Trade Agreement goes into effect. As tariffs are lifted on imports to Mexico, prices on produce drop sharply for Mexican farmers, sparking widespread migration from the land.

1994: U.S. Border Patrol launches Operation Gatekeeper, aimed at stopping illegal immigration along the traditional border crossing routes near San Diego. Over the next six years, the security clampdown is extended eastward, forcing migrants to cross inhospitable terrain.

1996: The Illegal Immigration Reform and Immigrant Responsibility Act is passed. Aimed in particular at the flood of illegal immigration from Mexico that followed NAFTA, the bill allocates more money for border security and increased penalties for illegal entry.

2000-2001: President Bush signals a willingness to work with Mexico on new immigration laws that would make it easier for Mexicans to work in the United States. The drive is halted after the Sept. 11 terrorist attacks.

2004: President Bush proposes a major overhaul of the immigration system to grant legal status to millions of undocumented workers in the United States.