Abstract
The United States and Mexico share a common history that includes some dramatic events such as the territorial struggles which often turned into established wars. In 1848 the USA annexed California and other Northern Mexican states. The episode generated important dissensions among the population, leading to a massive departure of the Mexicans who used to live in the annexed territories. An estimated 25% went to the Mexican territories. This episode is extremely relevant in understanding the tradition of migration between both countries. New borders did not lead to the end of ties and relationships between both areas. Thus, since the rest of the Mexicans had stayed in the United States, networks between the two countries were established, enabling and facilitating new flows in both directions. On the American side, the farmers travelled to Mexico to hire labor force that was also courted to work in the construction of railways and in the industrial sector of flourishing cities such as Chicago.
