Following the Mexican-American War (1846-1848), Mexico experienced significant territorial losses and political upheaval. Under the Treaty of Guadalupe Hidalgo, which ended the war, Mexico was forced to cede a significant portion of its northern territory, including California, Nevada, Utah, and parts of Arizona, Colorado, New Mexico, Wyoming, Kansas, and Oklahoma, to the United States. The loss of these territories was a significant blow to Mexico, both in terms of its territory and resources, and its national pride and identity.
The war also had a significant impact on Mexico's political system. The conflict had been sparked in part by tensions between Mexican centralists and regionalists, and the war exacerbated these divisions. In the aftermath of the war, Mexico underwent a period of political instability, with multiple governments and leaders vying for power. This instability continued for several decades and was marked by frequent changes in leadership, civil unrest, and economic struggles.
Overall, the Mexican-American War had a profound and lasting impact on Mexico, shaping its territorial boundaries, political system, and national identity.