The Mexican-American War, also known as the Mexican War or the Invasion of Mexico, was fought between 1846 and 1848. As a result of losing the war, Mexico lost almost half its territory, and the United States gained much of the land that makes up the American West.

The United States was inspired by the concept of Manifest Destiny—the idea that America had the right to expand across the continent.  The United States provoked the war in order to gain new land from Mexico.


Oil paint on canvas. Bent's fort is located directly in the center with the entrance on the side facing the viewer. There is a trail of covered wagons, horses and people entering the fort. On both sides of the tan fort there are Native American Tepees/tents, camps. Behind the fort is a herd of cattle and beyond that a river. There are mountains and a blue sky in the background. Painting done by Harry Miller, Works Progress Administration staff artist of SHS, in the 1930s.

Oil Painting, Bent's Fort Area View

History Colorado

The Treaty of Guadalupe Hidalgo was signed on February 2, 1848 and ended the Mexican-American War. By the terms of the treaty, the United States paid $15 million to Mexico and up to $3.25 million to pay off the claims of American citizens against Mexico. The United States claimed the Rio Grande as a boundary for Texas, ownership of California, half of New Mexico, most of Arizona, Nevada, Utah, and parts of Wyoming and Colorado. 

The 80,000 Mexican people living in those areas woke up in a new country. They were given the choice to move south to within Mexico’s new borders or stay in their homes and become American citizens with full civil rights. More than 90% of the people chose to stay in their homes and become U.S. citizens.

Life was not easy for these new American citizens. They were supposed to be able to keep their property, but various tactics resulted in their land being taken. For example, Mexican American landowners had to appear in English-speaking courts to keep their property. Unless they had enough money to travel to court and hire bilingual attorneys or interpreters, they often lost their land. According to the treaty, a Spanish or Mexican title should have been sufficient to prove land ownership. However, the United States exploited the difference between Mexican and American documents, and families often lost their land as a result. Losing land often forced people into poverty, creating a division of wealth based on race and ethnicity.

Upon ratification of the treaty, the United States Senate deleted the entirety of Article 10, a section meant to guarantee land rights for citizens living within the new borders. This decision deliberately broke promises the US government made with Mexican Americans, and it opened up loopholes to exploit these new citizens.

The Treaty of Guadalupe Hidalgo left a legacy of anger and a sense of injustice for the Mexican people and many Mexican Americans. Today, many people in the United States don’t see the treaty as significant, but in Mexican, Mexican American, Hispano, and Chicano history it was an incredibly important event that epitomized the problems with Manifest Destiny.





Resource Kits

Object Library

Museums

Standards for The Mexican-American War and the Treaty of Guadalupe Hidalgo

College, Career, and Civic Life (C3) Framework