In the war between Mexico and the United States, was from 1864-1848. The reason for this war was because the United States wanted to expand across the North America. Americans believe that they had the god given the right to expand across North America because they were more civilized also, more Americans were settling in western lands. The United States offered the Mexican government of large lump sum of money and Mexican Government refused to sell Half of the country. They saw America as a dangerous country and didn't want to reside next to them. They believe that if we live next to them we will eventually take over which we later date after the war. North America became for Americans and South America is where all the Spaniards now reside.