Explain how the Texas Revolution and the Mexican-American War expanded the territory of the United States.

Conflict with Mexico began when the United States annexed Texas as a state in 1845.
Mexico claimed that the new border between Texas and Mexico was the Nueces River, while the United States contested the border was the Rio Grande.
Fighting began when a detachment of U.S. cavalry was attacked near the Rio Grande.
Zachary Taylor and Winfield Scott led armies to a series of military successes that culminated in the capture of Mexico City in 1847.
Key Terms

Treaties of Velasco: Documents signed in Texas on May 14, 1836, intended to conclude the hostilities between Texas and Mexico and recognize Texas’ independence; however, Mexico never ratified them.
annexation: The permanent acquisition and incorporation of a territorial entity into another geo-political entity (either adjacent or non-contiguous).