Tensions between the United States and Mexico

In March 1845, James K. Polk became president. He wanted the nation to acquire the land between Texas and the Pacific Ocean. These sparsely populated territories, New Mexico and California, belonged to Mexico. Polk sought an opportunity to acquire these remote regions.

Mexico responds

The annexation of Texas enraged the Mexican government. Mexico had refused to recognize the Republic of Texas, and they broke off diplomatic ties with the U.S. after the vote for annexation.

Polk and Manifest Destiny

The U.S. needed to secure the boundary between Texas and Mexico. Texans put the border at the Rio Grande. Mexico maintained it was at the Nueces River. There were also disputes about money, and Polk wanted these issues resolved.

The boundary dispute

Slidell’s Trip

In the fall of 1845, Polk sent a special envoy to Mexico.

John Slidell arrived with a U.S. offer to cancel the $3 million in claims against Mexico in exchange for Mexico’s recognition of the Rio Grande as its boundary with the U.S. He was further authorized to pay Mexico up to $30 million to purchase New Mexico and California for the United States.

Neither of the rivals for Mexico’s presidency would meet with him. An angry Slidell recommended to Polk that Mexico be punished.

The Mexican-American War

American forces under Taylor advanced into northern Mexico. General Winfield Scott marched his forces into Mexico City. In a matter of months, U.S. forces had captured New Mexico and California. When their capital fell, the Mexican government was forced to give in.

The war starts

While Slidell was in Mexico, Polk ordered General Zachary Taylor to take his troops into the disputed border territory. The U.S. used the event of a minor skirmish to declare war on Mexico.

Fighting the war

The Treaty of Guadalupe Hildago (1848) forced Mexico to turn over a huge tract of land known as the Mexican Cession, while the U.S. paid Mexico $15 million. Debate continues over whether the Mexican-American War was justified.

Results of the war

The treaty also stated that Mexicans who remained in the state would be permitted to become U. S. citizens, and that they would be allowed to keep their property. However, the treaty was never fully honored. In the decades following the signing of the treaty, Mexican-Americans were stripped of nearly 20 million acres of their land by American businessmen, ranchers and railroad companies, as well as by the U.S. Department of the Interior and Department of Agriculture.

Taking Land