In the early 20th century, the Mexican Revolution of 1910–1920 caused a wave of violence and instability that led many Mexicans to flee to the United States. This wave of migration continued until the 1930s when the Great Depression made it difficult for Mexican immigrants to find work in the United States. As a result, many Mexicans returned to Mexico during this time.
After World War II, there was a resurgence in Mexican immigration to the United States. This was due in part to the Bracero Program, a wartime agreement that allowed Mexican workers to temporarily immigrate to the United States to work in agriculture. After the bracero program ended in 1964, many Mexicans remained in the United States illegally.
Since the 1960s, Mexican immigration to the United States has continued to increase. Many factors have contributed to this, including Mexico's high population growth rate, poverty, and violence.
Today, Mexican immigrants make up about 25% of all immigrants in the United States. They come from all socioeconomic backgrounds and work in a variety of industries. They have made enormous contributions to the US economy and culture.