From 1846 to 1848, the United States of America and Mexico went to war. There were several reasons why they did this, three of the most important were Manifest Destiny, the annexation of Texas, and the Slidell Mission. Americans gradually moved westward over two centuries, but in the 1830s and 1840s they crossed the continent. Say no to plagiarism. Get a Custom Essay on “Why Violent Video Games Should Not Be Banned”?Get the original essayTexas Americans vastly outnumbered the native Mexicans, and they sought full statehood for the province in order to obtain autonomy. Polk appointed John Slidell of Louisiana as minister to Mexico and asked him to offer up to $30 million to settle controversial claims and purchase California and New Mexico, the territory between Texas and California . Due to Manifest Destiny, the annexation of Texas, and the Slidell Mission, the President informed his cabinet that the United States "had many reasons to go to war." The 1840s were years of extraordinary territorial growth for the United States. Over a four-year period, the national domain increased by 1.2 million square miles, a gain of more than sixty percent. The process of territorial expansion was so rapid and dramatic that it came to be seen as an inexorable process, prompting many Americans to insist that their nation had a "manifest destiny": to dominate the continent. The idea of ​​Manifest Destiny held that Americans were superior to most other peoples in many ways. They were said to have a superior form of government, a superior culture, and a superior religion. For these reasons, it was said, they were destined by God to expand their territory. This attitude led to westward migration. First, it contributed to the expansion of the American territory. This helped lead to the Mexican-American War because it fostered the attitude that America deserved all this land more than the Mexicans. America's God-given destiny made taking Mexico's lands acceptable. The same attitude applied to the Indians as American settlers moved west. The idea was that the Indians were so inferior that they did not deserve the use of the land. They had to be moved and the land had to go back to Americans who deserved it and would use it well. The spirit of “Manifest Destiny” permeated the United States during the Reform Era, the decades before the Civil War. John L. O'Sullivan, editor of the influential United States Magazine and Democratic Review, gave its name to the expansionist movement in 1845 when he wrote that it was "the fulfillment of our manifest destiny to expand the continent allocated by Providence for freedom.” development of our millions who multiply every year. Manifest Destiny was driven by nationalism and an idealistic vision of human perfectibility. It was America's duty to expand freedom and democratic institutions across the continent. Texas gained independence from Mexico in 1836. Initially, the United States refused to incorporate it into the union, largely because Northern political interests were opposed to adding a new slave state. . Nonetheless, annexation proceedings were quickly initiated after the election of Polk in 1844, who campaigned for Texas to be "reannexed" and the Oregon Territory to be "reoccupied." Polk also had eyes.