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.