page_title: Presidency of James K. Polk
section_title: Postwar and the territories
hierarchical_section_title: Presidency of James K. Polk / Foreign affairs / Mexican–American War / Postwar and the territories
caption_attribution_description: Map of the states and territories of the United States as it was from March 1845 to December 1845. On March 3 1845, Florida Territory was admitted as the state of Florida. On December 29 1845, the Republic of Texas and all of its claimed lands were admitted as the state of Texas.
context_page_description: The presidency of James K. Polk began on March 4, 1845, when James K. Polk was inaugurated as President of the United States, and ended on March 4, 1849. He was a Democrat, and assumed office after defeating Whig Henry Clay in the 1844 presidential election. Polk left office after one term, fulfilling a campaign pledge he made in 1844, and he was succeeded by Whig Zachary Taylor. A close ally of Andrew Jackson, Polk's presidency reflected his adherence to the ideals of Jacksonian democracy and manifest destiny.
  Polk was the last strong pre-Civil War president, having met during his four years in office every major domestic and foreign policy goal set during his campaign and the transition to his administration. Polk's presidency was particularly influential in U.S. foreign policy, and his presidency saw the last major expansions of the Contiguous United States. When Mexico rejected the U.S. annexation of Texas, Polk achieved a sweeping victory in the Mexican–American War, which resulted in the cession by Mexico of nearly the whole of what is now the American Southwest.
context_section_description: Polk had been anxious to establish a territorial government for Oregon once the treaty was effective in 1846, but the matter became embroiled in the arguments over slavery, though few thought Oregon suitable for that institution. A bill to establish an Oregon territorial government passed the House after being amended to bar slavery; the bill died in the Senate when opponents ran out the clock on the congressional session. A resurrected bill, still barring slavery, again passed the House in January 1847, but it was not considered by the Senate before Congress adjourned in March. By the time Congress met again in December, California and New Mexico were in U.S. hands, and Polk in his annual message urged the establishment of territorial governments in California, New Mexico, and Oregon. The Missouri Compromise had settled the issue of the geographic reach of slavery within the Louisiana Purchase territories by prohibiting slavery in states north of 36°30′ latitude, but Polk sought to extend this line into the newly acquired territory. If extended to the Pacific, this would have made slavery illegal in Northern California, but would have allowed it in Southern California. A plan to accomplish the extension was defeated in the House by a bipartisan alliance of Northerners. As the last congressional session before the 1848 election came to a close, Polk signed the lone territorial bill passed by Congress, which established the Territory of Oregon and prohibited slavery in it.
  When Congress reconvened in December 1848, Polk again called for the establishment territorial governments in California and New Mexico, a task made especially urgent by the onset of the California Gold Rush. However, the divisive issue of slavery blocked any such legislation. Polk made it clear that he would veto a territorial bill that would have had the laws Mexico apply to the southwest territories until Congress, considering it to be the Wilmot Proviso in another guise. It was not until the Compromise of 1850 that the matter of the territories was resolved.
caption: United States states and territories when Polk entered office
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