The Mexican-American War was a conflict between the United States and Mexico. This was a land war, Mexico was fighting to keep the land they had acquired since their independence from Spain. The United States wanted more of Mexico's northern lands and especially Texas. One of the primary causes of the Mexican-American War was “Manifest Destiny,” which held that the United States had a God-given right to colonize the entire continent of North America. Another major cause of the Mexican-American War began with the Texas War of Independence. By 1820 Mexico had actually allowed Americans to live in Mexican territory, Mexico needed settlers and began to colonize it, but the only difference was that the Mexican government taxed and controlled the population in their territory. Americans who had this idea of ​​manifest destiny did not want to live under Mexican rule. Large numbers of Americans migrated west in search of land, most of those areas had people living in them but that didn't stop them, they thought the Americans would do a better job of governing the land than the native Indians and to the Mexicans. Manifest Destiny was a vision that most Americans and especially President Polk had in the 18th century, which led to America stealing territory that was not rightfully theirs. This belief that the United States had a God-given right to take control and "humanize" the North American continent became more famous as more Americans settled the western lands. The fact that most of the former regions recently had people living there was often overlooked, with the belief that the Americans, with their high standards and Christian morals, could be better at governing than the Native Americans and Mexicans . .... half of the document ...... is approved by the US Congress and also by the Mexican Congress. The treaty provided for the extension of the northern partitions of Mexico to the United States. In exchange, the United States agreed to pay $15 million to Mexico as payment for the acquired region. The determination of the singular Mexican warrior amply demonstrates the difficulties encountered by the United States in ending the war. The lack of leadership for the Mexican military was horrendous when compared to American authority. Furthermore, in many battles, the prevailing guns of the US artillery divisions and the creative plans of the officers turned the tables against the Mexican army. This war cost the United States approximately $100 million and ended the lives of more than 13,000 Americans. America had crushed its weaker and somewhat disoriented southern neighbor, but not without paying a terrible price.