section_path: History/Westward expansion and Civil War (1800 – 1865)
section_name: Westward expansion and Civil War (1800 – 1865)
paragraph_text: Westward expansion and Civil War (1800 – 1865)
  
  In the late 18th century, American settlers began to expand westward in larger numbers, many with a sense of manifest destiny. The Louisiana Purchase of 1803 from France nearly doubled the territory of the United States. Lingering issues with Britain remained, leading to the War of 1812, which was fought to a draw. Spain ceded Florida and its Gulf Coast territory in 1819. The Missouri Compromise of 1820, which admitted Missouri as a slave state and Maine as a free state, attempted to balance the desire of northern states to prevent the expansion of slavery into new territories with that of southern states to extend it there. Primarily, the compromise prohibited slavery in all other lands of the Louisiana Purchase north of the 36°30′ parallel. As Americans expanded further into territory inhabited by Native Americans, the federal government implemented policies of Indian removal or assimilation. The most significant such legislation was the Indian Removal Act of 1830, a key policy of President Andrew Jackson. It resulted in the Trail of Tears (1830–1850), in which an estimated 60,000 Native Americans living east of the Mississippi River were forcibly removed and displaced to lands far to the west, causing 13,200 to 16,700 deaths along the forced march. Settler expansion as well as this influx of Indigenous peoples from the East resulted in the American Indian Wars west of the Mississippi.
  
  The United States annexed the Republic of Texas in 1845, and the 1846 Oregon Treaty led to U.S. control of the present-day American Northwest. Dispute with Mexico over Texas led to the Mexican–American War (1846 – 1848). After the victory of the U.S., Mexico recognized U.S sovereignty over Texas, New Mexico, and California in the 1848 Mexican Cession; the cession's lands also included the future states of Nevada, Colorado and Utah. The California gold rush of 1848–1849 spurred a huge migration of white settlers to the Pacific coast, leading to even more confrontations with Native populations. One of the most violent, the California genocide of thousands of Native inhabitants, lasted into the mid-1870s. Additional western territories and states were created.
  
  During the colonial period, slavery had been legal in the American colonies, becoming the main labor force in the large-scale, agriculture-dependent economies of the Southern Colonies from Maryland to Georgia. The practice began to be significantly questioned during the American Revolution, and spurred by an active abolitionist movement that had reemerged in the 1830s, states in the North enacted laws to prohibit slavery within their boundaries. At the same time, support for slavery had strengthened in Southern states, with widespread use of inventions such as the cotton gin (1793) having made slavery immensely profitable for Southern elites. Throughout the 1850s, this sectional conflict regarding slavery was further inflamed by national legislation in Congress and decisions of the Supreme Court: The Fugitive Slave Act of 1850 mandated the forcible return to their owners in the South of slaves taking refuge in non-slave states. The Kansas–Nebraska Act of 1854 effectively gutted the anti-slavery requirements of the Missouri Compromise. Finally, in its Dred Scott decision of 1857, the Supreme Court ruled against a slave brought into non-slave territory and declared the entire Missouri Compromise to be unconstitutional. These events exacerbated tensions between North and South that would culminate in the American Civil War (1861–1865).
  
  Beginning with South Carolina, 11 slave-state governments voted to secede from the United States in 1861, joining to create the Confederate States of America. All other states remained in the Union. War broke out in April 1861 after the Confederacy bombarded Fort Sumter. Following the January 1, 1863 Emancipation Proclamation, many freed slaves joined the Union army. The war began to turn in the Union's favor following the 1863 Siege of Vicksburg and Battle of Gettysburg, and the Confederates surrendered in 1865 after the Union's victory in the Battle of Appomattox Court House.