Answer:
The Mexican-American War had significant effects on both Mexican citizens and American citizens living in the Southwest between 1848 and 1870. The war, which was fought from 1846 to 1848, ended with the signing of the Treaty of Guadalupe Hidalgo, which ceded about half of Mexico's territory to the United States. This had a major impact on Mexican citizens living in the ceded territory, as they were suddenly living under American rule and subject to American laws and institutions. Many Mexican citizens were also displaced by the war and the subsequent treaty.
For American citizens living in the Southwest, the Mexican-American War and the resulting treaty led to an expansion of American territory and an influx of new settlers. This increased competition for resources and land, and led to conflicts between American settlers and Mexican citizens, as well as Native American tribes. The war and its aftermath also contributed to the development of a distinct American Southwest culture, blending elements of Mexican and American traditions. Overall, the Mexican-American War had complex and far-reaching effects on the people living in the Southwest.