When mexico and the united states last fought, what piece of land changed hands? answers?

Officially, the last time Mexico and the U. S. fought was during the Mexican-American War (1846-1848) when most of the U. S. Southwest changed hands.

Answer: The correct answer is : In 1848 the Treaty of Guadalupe Hidalgo was signed, which sealed the triumph of the United States in which Mexico ceded almost half of its land to the United States, which is currently: California, Arizona, Nevada, New Mexico, Utah, a part of Colorado and Wyoming, besides the Rio Grande was recognized as the border with the United States. The people who inhabited these territories were promised US citizenship when these ceded lands became states.