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Following their victory in the French and Indian War, Britain began to assert greater control over local colonial affairs, resulting in colonial political resistance; one of the primary colonial grievances was a denial of their rights as Englishmen, particularly the right to representation in the British government that taxed them. To demonstrate their dissatisfaction and resolve, the First Continental Congress met in 1774 and passed the Continental Association, a colonial boycott of British goods that proved effective. The British attempt to then disarm the colonists resulted in the 1775 Battles of Lexington and Concord, igniting the American Revolutionary War. At the Second Continental Congress, the colonies appointed George Washington commander-in-chief of the Continental Army, and created a committee that named Thomas Jefferson to draft the Declaration of Independence. Two days after passing the Lee Resolution to create an independent nation the Declaration was adopted on July 4, 1776.[70] The political values of the American Revolution included liberty, inalienable individual rights; and the sovereignty of the people;[71] supporting republicanism and rejecting monarchy, aristocracy, and all hereditary political power; civic virtue; and vilification of political corruption.[72] The Founding Fathers of the United States, who included Washington, Jefferson, John Adams, Benjamin Franklin, Alexander Hamilton, John Jay, James Madison, Thomas Paine, and many others, were inspired by Greco-Roman, Renaissance, and Enlightenment philosophies and ideas.[73][74]
The Articles of Confederation and Perpetual Union were ratified in 1781 and established a decentralized government that operated until 1789.[70] After the British surrender at the siege of Yorktown in 1781 American sovereignty was internationally recognized by the Treaty of Paris (1783), through which the U.S. gained territory stretching west to the Mississippi River, north to present-day Canada, and south to Spanish Florida.[75] The Northwest Ordinance (1787) established the precedent by which the country's territory would expand with the admission of new states, rather than the expansion of existing states.[76] The U.S. Constitution was drafted at the 1787 Constitutional Convention to overcome the limitations of the Articles. It went into effect in 1789, creating a federal republic governed by three separate branches that together ensured a system of checks and balances.[77] George Washington was elected the country's first president under the Constitution, and the Bill of Rights was adopted in 1791 to allay skeptics' concerns about the power of the more centralized government.[78][79] His resignation as commander-in-chief after the Revolutionary War and his later refusal to run for a third term as the country's first president established a precedent for the supremacy of civil authority in the United States and the peaceful transfer of power.[80][81]
Westward expansion and Civil War (1800–1865)
The Louisiana Purchase of 1803 from France nearly doubled the territory of the United States.[82][83] Lingering issues with Britain remained, leading to the War of 1812, which was fought to a draw.[84][85] Spain ceded Florida and its Gulf Coast territory in 1819.[86] In the late 18th century, American settlers began to expand westward, many with a sense of manifest destiny.[87][88] 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. The compromise further prohibited slavery in all other lands of the Louisiana Purchase north of the 36°30′ parallel.[89] As Americans expanded further into land inhabited by Native Americans, the federal government often applied policies of Indian removal or assimilation.[90][91] The most significant removal legislation in U.S. history was the Indian Removal Act of 1830. It culminated 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. The Trail of Tears resulted in anywhere from 13,200 to 16,700 deaths.[92] These and earlier organized displacements prompted a long series of American Indian Wars west of the Mississippi.[93][94] The Republic of Texas was annexed in 1845,[95] and the 1846 Oregon Treaty led to U.S. control of the present-day American Northwest.[96] Victory in the Mexican–American War resulted in the 1848 Mexican Cession of California, Nevada, Utah, and much of present-day Colorado and the American Southwest.[87][97] 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 early 1870s,[98] just as additional western territories and states were created.[99]
During the colonial period, slavery had been legal in the American colonies, though the practice began to be significantly questioned during the American Revolution.[100] Spurred by an active abolitionist movement that had reemerged in the 1830s, states in the North enacted anti-slavery laws.[101] At the same time, support for slavery had strengthened in Southern states with inventions such as the cotton gin (1793), which had long made the institution profitable for Southern elites.[102][103][104] Throughout the 1850s, this sectional conflict regarding slavery was further inflamed by legislation in Congress and decisions of the Supreme Court: The Fugitive Slave Act of 1850 mandated the return of slaves taking refuge in non-slave states to their owners in the South. The Kansas–Nebraska Act of 1854 effectively gutted the anti-slavery requirements of the Missouri Compromise.[105] Finally, in its Dred Scott decision of 1857, the Supreme Court ruled against a slave brought into non-slave territory and declared the Missouri Compromise to be unconstitutional. These events exacerbated tensions between North and South that would culminate in the American Civil War (1861–1865).[106][107] Eleven slave states seceded and formed the Confederate States of America, while the other states remained in the Union.[108][109] War broke out in April 1861 after the Confederates bombarded Fort Sumter.[110][111] After the January 1863 Emancipation Proclamation, many freed slaves joined the Union army.[112] The war began to turn in the Union's favor following the 1863 Siege of Vicksburg and Battle of Gettysburg, and the Confederacy surrendered in 1865 after the Union's victory in the Battle of Appomattox Court House.[113] The Reconstruction era followed the war. After the assassination of President Abraham Lincoln, Reconstruction Amendments were passed to protect the rights of African Americans. National infrastructure, including transcontinental telegraph and railroads, spurred growth in the American frontier.[114]