During the Seven Years’ War (1756–1763), known in the U.S. as the French and Indian War, British forces captured Canada from the French. With the creation of the Province of Quebec, Canada’s francophone population would remain isolated from the English-speaking colonial dependencies of Nova Scotia, Newfoundland and the Thirteen Colonies. Excluding the Native Americans who lived there, the Thirteen Colonies had a population of over 2.1 million in 1770, about a third that of Britain. Despite continuing new arrivals, the rate of natural increase was such that by the 1770s only a small minority of Americans had been born overseas. The colonies’ distance from Britain had allowed the development of self-government, but their unprecedented success motivated British monarchs to periodically seek to reassert royal authority.
Independence and expansion:
The American Revolutionary War fought by the Thirteen Colonies against the British Empire was the first successful war of independence by a non-European entity against a European power in modern history. Americans had developed an ideology of “republicanism“, asserting that government rested on the will of the people as expressed in their local legislatures. They demanded their “rights as Englishmen” and “no taxation without representation“. The British insisted on administering the empire through Parliament, and the conflict escalated into war.
The Second Continental Congress unanimously adopted the Declaration of Independence on July 4, 1776; this day is celebrated annually as Independence Day. In 1777, the Articles of Confederation established a decentralized government that operated until 1789.
After its defeat at the Siege of Yorktown in 1781, Britain signed a peace treaty. American sovereignty became internationally recognized, and the country was granted all lands east of the Mississippi River. Tensions with Britain remained, however, leading to the War of 1812, which was fought to a draw. Nationalists led the Philadelphia Convention of 1787 in writing the United States Constitution, ratified in state conventions in 1788. The federal government was reorganized into three branches in 1789, on the principle of creating salutary checks and balances. George Washington, who had led the Continental Army to victory, was the first president elected under the new constitution. The Bill of Rights, forbidding federal restriction of personal freedoms and guaranteeing a range of legal protections, was adopted in 1791.
Beginning in the late 18th century, American settlers began to expand westward, prompting a long series of American Indian Wars. The 1803 Louisiana Purchase almost doubled the nation’s area, Spain ceded Florida and other Gulf Coast territory in 1819, the Republic of Texas was annexed in 1845 during a period of expansionism, and the 1846 Oregon Treaty with Britain led to U.S. control of the present-day American Northwest. Victory in the Mexican–American War resulted in the 1848 Mexican Cession of California and much of the present-day American Southwest, making the U.S. span the continent.
The California Gold Rush of 1848–1849 spurred migration to the Pacific coast, which led to the California Genocide and the creation of additional western states. The giving away of vast quantities of land to white European settlers as part of the Homestead Acts, nearly 10% of the total area of the United States, and to private railroad companies and colleges as part of land grants spurred economic development. After the Civil War, new transcontinental railways made relocation easier for settlers, expanded internal trade, and increased conflicts with Native Americans. In 1869, a new Peace Policy nominally promised to protect Native Americans from abuses, avoid further war, and secure their eventual U.S. citizenship. Nonetheless, large-scale conflicts continued throughout the West into the 1900s.