USA HISTORY

Detailed explanation-1: -It stemmed from the annexation of the Republic of Texas by the U.S. in 1845 and from a dispute over whether Texas ended at the Nueces River (the Mexican claim) or the Rio Grande (the U.S. claim).

Detailed explanation-2: -The dispute surrounding assigning the border at the Río Grande or at Nueces River, coupled with the U.S. annexation of Texas in 1845, set the Mexican-American War into motion.

Detailed explanation-3: -This was known as the Mexican Cession and included present-day Arizona and New Mexico and parts of Utah, Nevada, and Colorado (see Article V of the treaty). Mexico also relinquished all claims to Texas and recognized the Rio Grande as the southern boundary with the United States (see Article V).