The correct answer to this open question is the following.
The Mexican-American War impacted Latinos in the west in that with the annexation of territories like California, Nevada, and Arizona that used to be inhabited by Mexicans, now these people became Americans. When the United States won the war, México and the US signed the Treaty of Guadalupe Hidalgo on February 2, 1848. Mexico agreed to cede the states of California, Nevada, Utah, New Mexico, and part of Colorado.