The Mexican War

By the 1840s, territory in the United States was spreading in all directions. Some people felt that the country should not spread from the Atlantic to the Pacific Oceans and from Canada to the Rio Grande. But because of its economic and political superiority and growing population, many felt that it was the destiny of America to rule North America. This was known as the Manifest Destiny.

The president at the time was James Polk. He believed very strongly in the Manifest Destiny. He offered to buy the Mexican territory, which consisted of the California and New Mexico areas, which also included Arizona. Mexico refused. President Polk sent troops into a territory near the Rio Grande that both countries claimed as their own. American soldiers as well as Mexican soldiers were killed in the small conflict. President Polk claimed that American blood had been shed. He asked Congress to declare war on Mexico. Congress did so.

In 1848, Mexico and the United States signed a peace treaty. The treaty stated that the United States received all the land that today makes up California, Nevada, and Utah. It also received most of what is now the state of Arizona, parts of Wyoming, New Mexico, and Colorado. In return, the United States paid Mexico 15 million dollars. This is known as the Mexican Cession.