Discuss the process of ‘racialization’ of the Mexican population in California, Arizona and Texas

Need to write a 3 page article using the text book Michael Ornelas Between the Conquests: The Early Chicano Historical Experience, 5th ed and the question is as follow :  
It can be argued that the process of ‘racialization’ of the Mexican population began shortly after
the United States incorporation of the Mexican territories through the Treaty of Guadalupe Hidalgo.
Discuss the process of ‘racialization’ of the Mexican population in California, Arizona and
Texas. Utilize the Menchaca article, pages 285-307.