What two migration patterns have changed Mexico's population?

Answer 1

When Mexico became an overseas territory of Spain, many immigrants began to populate the region; many of them also having interracial marriages with the American Natives, becoming the new mestizo race, which now makes the majority of the Mexican population.

Later, when Mexico won its independence against Spain, it relaxed its Immigration policies, allowing Anglo settlers to populate the northern territories. Long story short, these immigrants revolted, successfully becoming the Texas Republic in 1836.

At the end of the Mexican-American War (1846-1848) up to 50,000 Mexicans who populated New Mexico, Arizona, California and Colorado were absorbed within the American population. They however, lost most of their rights and lands to Anglo settlers.

Much later, at the beginning of the 20th century, many Mexican people began to emigrate from Mexico into the US, especially due to the high demand of laborers and cowhands in California and Texas. This process accelerated during the last half of the century, reaching a peak at the beginnings of the 21st century. Since then, less and less people emigrate from Mexico, either because of the stringent immigration laws passed by the US, as well as the ongoing industrialization of Mexico.