President William Henry Harrison died a month after his inauguration in 1841. He was succeeded by John Taylor, who immediately set forth an entirely different agenda. Tyler started by vetoing measures to revive the national bank. At the same time, he sought the annexation of Texas to the Union as a slave state. The Texas territories had won their independence from Mexico in 1836.
The idea of constantly reaching out for more and more territory in the west was first called Manifest Destiny by John L. Sullivan. Sullivan was editor of The Democratic Review. He stated in his essay that it was our right of Manifest Destiny to spread over and possess the whole continent, and that that right was God given (Providence). The idea of Manifest Destiny was quickly accepted nationally by writers and politicians alike. Previously, President Andrew Jackson had led the movement for expansion. He had clearly stated his motives when he told of his intentions to acquire all of Spanish North America. Jackson had repeatedly been quoted as saying that American security depended on America expanding in the Southwest and along the Gulf of Mexico. Jackson especially did not want foreign powers in possession of heads of the branches of the Mississippi River. He said that the, “god of the universe had intended the great valley to be one nation.” The great nation he was referring to was the United States. President Jackson believed that the British, Spanish, and Native Americans were a threat to Americas security. Eventually, he would defeat them all.
The American people loved the idea of Manifest Destiny. It stated that American expansion southward, westward, and northward were inevitable, destined by Providence (God), and justified in the name of progress. So when President Tyler attempted introduced a bill that would allow annexation of states by a simple majority instead of a 2/3rds vote it was quickly passed in both houses before begin signed on March 1, 1845. Soon afterward, Texas was admitted as a slave state.
President Tyler was succeeded by President James Knox Polk who was an admirer of President Jackson's policies. President Polk may have wanted Spanish North America even more than Jackson. Polk was extremely excited about the possibility of expanding into California. California had amazing possibilities with its natural harbors. At the time, Polk wanted to expand trade with China, and he felt he could do that if California were admitted into the Union.
Polk would next attempt to buy ½ of the country of Mexico from its government, and when the answer was no, he invaded the country. After winning the Mexican/American War Polk seized 1/3rd of the country. A section that had just 1% of the population. Following the signing of the Treaty of Guadalupe Hildalgo, the United States paid Mexico $15 million for California, Utah, Wyoming, Arizona, New Mexico, and Nevada. At the same time, Polk arranged a compromise in which he obtained Oregon from the British. Then, immediately following the Civil War, Secretary of the State William Seward used the Manifest Destiny when he bought Alaska from the Russians. The Manifest Destiny argument would also be used in the rationalization for the colonization of the Philippines after the Spanish American War.