The Treaty of Guadalupe Hidalgo was extremely important for both the United States and Mexico. This treaty was signed in order to mark the end of the Mexican-American War in 1848.
The treaty gave $15 million USD to Mexico. However, it also led to an enormous loss of territory for Mexico. Mexico gave up the land that nowadays corresponds to half of New Mexico, most of Arizona, Nevada, and Utah and Colorado. It also gave American citizenship to many of the people in those areas.
The adoption of such large numbers of people brought a cultural change to the United States. Moreover, the country also adopted many of the cultural practices that were common in these regions. The treaty had a large effect on the future of the country, as it pushed the agenda of imperialism and Manifest Destiny.