In the 19th century US, Manifest Destiny was a belief that was widely held that the destiny of American settlers was to expand and move across the continent to spread their traditions and their institutions, while at the same time enlightening more primitive nations. And the American settlers of the time considered Indians and Hispanics to be inferior and therefore deserving of cultivation. The settlers considered the United States to be the best possible way to organize a country so they felt the need to remake the world in the image of their own country.
Many Americans believed that God blessed the growth of American nation and even demanded of them to actively work on it. Since they were sure of their cultural and racial superiority, they felt that their destiny was to spread their rule around and enlighten the nations that were not so lucky. The settlers firmly believed in the virtue of American people and the mission to impose their virtuous – mainly Puritan – way of life on everybody else. This rhetorical background served to explain the acquisition of territories or reasons to go to war, such as the war with Mexico in 1840s.