In order to understand the war with Mexico, you need to understand:

The Mexican American War President James K. Polk General Zachary Taylor

Border Dispute The U.S. and Mexico had a different opinion on where the border between Texas and Mexico was.

War of Aggression President Polk sent General Taylor to the area that the U.S. considered it’s border. Predictably, Taylor’s troops were attached by the Mexican army. Polk had what he wanted, a war with Mexico.

What did the U.S. want from war with Mexico? Land Manifest Destiny Resources

Treaty of Guadalupe Hidalgo was signed ending the war.

The Mexican Cession

Mexican Cession Mexico had to give up a great deal of land at the conclusion of the war. This territory included all of the present-day states of California, Nevada, and Utah and also parts of Arizona, Colorado, New Mexico, Utah, and Wyoming.

Territorial Expansion