Question

what was the event leading Mexcian Cession to becoming part of the U.S.? in 2-3 sentences

Answer 1

The event that led to the Mexican Cession becoming part of the U.S. was the Mexican-American War. The war was sparked by the annexation of Texas by the U.S. in 1845 and the subsequent border dispute, resulting in the U.S. victory and the signing of the Treaty of Guadalupe Hidalgo in 1848, which ceded a large portion of Mexican territory to the U.S.