For Mexico, the war was a military disaster from the start, but the Mexican government was unwilling to sue for peace or concede the loss of its northern lands.
After the Fall of Mexico city, the Mexican government had little choice but to agree to U.S terms.
The Treaty of Guadalupe Hidalgo was negotiated by Mexico and an American diplomat.
1. Mexico recognized the Rio Grande as the southern border of Texas.
2. The United States took possession of the former Mexican provinces of California and New Mexico (Nevada, Utah, Colorado, Arizona etc)--the Mexican Cession. The U.S paid $15 million and assumed responsibility for any claims of American citizens against Mexico.
The US territory increases by ⅓ whilst Mexico loses about half of its territory.