1795 - 1849
James K. Polk
Mexico has passed the boundary of the United States, has invaded our territory and shed American blood upon the American soil. She has proclaimed that hostilities have commenced, and that the two nations are now at war. War Message to Congress
Under James Knox Polk, the United States grew by more than a million square miles, adding territory that now composes the states of Arizona, Utah, Nevada, California, Oregon, Idaho, Washington, much of New Mexico, and portions of Wyoming, Montana, and Colorado. More than any other President, Polk pursued "Manifest Destiny," a phrase coined by his fellow Jacksonian Democrat, John L. O'Sullivan, to express the conviction that Providence had foreordained the United States to spread its republican institutions across North America. He accomplished every major goal that he set for himself as President and in the process successfully waged war against Mexico, obtaining for the United States most of its present boundaries as a nation.
James Knox Polk and the war with Mexico
Watch Daniel Walker Howe, professor at Oxford University and UCLA, talk about President Polk and the Mexican War