Which event happened at the end of the mexican war? the us gave up texas to mexico. borders returned to their prewar locations. the us gained a large area in the west from mexico.

The correct answer is:  

The US gained a large area in the West from Mexico.

The 1848 Treaty of Guadalupe Hidalgo concluded the Mexican War and forced the Mexican Cession of the northern areas of Alta California and Santa Fe de Nuevo México to the United States. Mexico recognized the loss of what became the State of Texas and acknowledged the Rio Grande as its northern frontier with the U.S.