The Mexican-American War period refers to the time between 1846 and 1848 when the United States engaged in a conflict with Mexico over territorial disputes. This war resulted in significant territorial gains for the United States.
Related terms
Manifest Destiny: The belief during this time period that it was America's destiny to expand its territory from coast to coast.
Treaty of Guadalupe Hidalgo: A treaty signed in 1848 that ended the Mexican-American War and resulted in Mexico ceding large portions of land to the United States, including California, Nevada, Utah, Arizona, New Mexico, and parts of Colorado and Wyoming.
Western Expansion: The movement of settlers into western territories gained by the United States during this time period.