The origins of street gangs across the United States can be traced back to immigration patterns and settlements. However, in the Southwest, they can be traced back to the Mexican American War of 1846-1848. Under the Treaty of Guadalupe Hidalgo, Mexico was forced to give up almost half of its territory which included what today is California, Nevada, Utah, Arizona, New Mexico, Texas, and half of Colorado, where Mexicans and Spaniards in those areas were given the opportunity to become naturalized U.S. citizens, and property owners were to have full protection and enjoyment of their real property. However, many were forced to give up their land by hostile takeover, lynching's, and death, and when cases were brought to court citing the protection of the Treaty, the judicial process systematically denied their claims. The result was a high percentage of Mexicans and their descendants being dispossessed of their property and the origin of systematic discrimination and oppression against the Mexican American community. In 2000, Congress finally acknowledged and found that the loss of property in the Southwest by the Mexican American community has had severe adverse effects on our people, but it has done nothing to remedy the disenfranchisement and dispossession that resulted.
After the Treaty, Mexicans in the Southwest were just beginning to shape an identity as Americans in the United States, but started off with annexation by conquest and strained race relations. Having just lost their territory, their motherland, their homes, their identity, and facing harsh discrimination, they were also told to "go home" by the Anglo population. But, they were already home. So our people now became alienated in their own homeland, they were treated as substandard citizens, and their psychological state began to adopt a position of protectionism. Many Mexican Americans believed, still today, that their homeland was stolen from them and their ancestors, thus the school of thought that formed around that time was fueled by that concept. As the turn of the century approached, accelerated by the Mexican Revolution and cheap labor needed in the Southwest and the Midwest, Mexican immigration began to increase following a well-traveled road that paralleled the railroad that started in Jalisco and Michoacán. (There is also a popular song that celebrates this route.)
Beginning in the 1890s, Mexican immigrant youth flocked around urban areas all through the Southwest to establish a visible male bonding tradition that already existed in Mexico, and became commonplace in urban areas like El Paso, Albuquerque, and Los Angeles. They were called palomillas, or flock of doves, who joined other marginalized Mexican Americans in their struggle against cultural, racial, and socioeconomic barriers enforced by the Anglo-American community. They began to settle in geographically isolated areas that were considered undesirable, and began forming unique barrios that could not effectively assimilate into Anglo culture, and so they began forming their own subculture. It wasn't until the famous Mexican philosopher and politician of the Revolution, Jose Vasconcelos, wrote about the cosmic race and the people of the Southwest, that the Mexican American people began having a unique voice and identity they could embrace, which for many started as gang culture.