How did Manifest Destiny influence the Mexican-American War?

Manifest Destiny was the 19th-century belief that the United States possessed a divinely ordained right to expand its borders westward to the Pacific Ocean. This ideology served as a powerful justification for American territorial acquisitions, including the Republic of Texas, New Mexico, and California.123

During the 1840s, President James K. Polk utilized this expansionist sentiment to pursue the acquisition of Mexican territories. When diplomatic efforts to purchase California and New Mexico failed, and following the annexation of Texas, the U.S. engaged in a border dispute with Mexico regarding the boundary between the Nueces River and the Rio Grande.42

Manifest Destiny provided the rationale for the Mexican-American War, as the U.S. sought to fulfill its perceived continental destiny by force. The resulting Treaty of Guadalupe Hidalgo ultimately secured vast territories for the U.S., expanding its landmass by approximately one-third and achieving the goal of reaching the Pacific.24