The date of the start of the history of the United States is a subject of constant debate among historians. Older textbooks start with the arrival of Christopher Columbus in 1492 and emphasize the European background, or they start around 1600 and emphasize the American frontier. In recent decades American schools and universities typically have shifted back in time to include more on the colonial period and much more on the prehistory of the Native peoples.
Indigenous people lived in what is now the United States for thousands of years before European colonists began to arrive, mostly from England, after 1600. The Spanish had small settlements in Florida and the Southwest, and the French along the Mississippi River and the Gulf Coast. By the 1770s, thirteen British colonies contained two and a half million people along the Atlantic coast east of the Appalachian Mountains. In the 1760s the British government imposed a series of new taxes while rejecting the American argument that any new taxes had to be approved by the people (see Stamp Act 1765). Tax resistance, especially the Boston Tea Party (1774), led to punitive laws (the Intolerable Acts) by Parliament designed to end self-government in Massachusetts. American Patriots (as they called themselves) adhered to a political ideology called republicanism that emphasized civic duty, virtue, and opposition to corruption, fancy luxuries and aristocracy.
All thirteen colonies united in a Congress that called on them to write new state constitutions. After armed conflict began in Massachusetts, Patriots drove the royal officials out of every colony and assembled in mass meetings and conventions. Those Patriot governments in the colonies unanimously empowered their delegates to Congress to declare independence. In 1776, Congress declared that there was a new, independent nation, the United States of America, not just a collection of disparate colonies. With large-scale military and financial support from France and military leadership by General George Washington, the American Patriots rebelled against British rule and succeeded in the Revolutionary War. The peace treaty of 1783 gave the new nation the land east of the Mississippi River (except Florida and Canada, and Spain disputed the Mississippi Territory until 1795) and confirmed Great Britain's recognition of the United States as a nation. The central government established by the Articles of Confederation proved ineffectual at providing stability, as it had no authority to collect taxes and had no executive officer. Congress called a convention to meet secretly in Philadelphia in 1787 to revise the Articles of Confederation. It wrote a new Constitution, which was adopted in 1789. In 1791, a Bill of Rights was added to guarantee inalienable rights. With Washington as the Union's first president and Alexander Hamilton his chief political and financial adviser, a strong central government was created. When Thomas Jefferson became president he purchased the Louisiana Territory from France, doubling the size of the United States. A second and final war with Britain was fought in 1812.
Encouraged by the notion of Manifest Destiny, federal territory expanded all the way to the Pacific. The U.S. always was large in terms of area, but its population was small, only 4 million in 1790. Population growth was rapid, reaching 7.2 million in 1810, 32 million in 1860, 76 million in 1900, 132 million in 1940, and 321 million in 2015. Economic growth in terms of overall GDP was even faster. However the nation's military strength was quite limited in peacetime before 1940. The expansion was driven by a quest for inexpensive land for yeoman farmers and slave owners. The expansion of slavery was increasingly controversial and fueled political and constitutional battles, which were resolved by compromises. Slavery was abolished in all states north of the Mason–Dixon line by 1804, but the South continued to profit off the institution, producing high-value cotton exports to feed increasing high demand in Europe. The 1860 presidential election of Republican Abraham Lincoln was on a platform of ending the expansion of slavery and putting it on a path to extinction. Seven cotton-based deep South slave states seceded and later founded the Confederacy months before Lincoln's inauguration. No nation ever recognized the Confederacy, but it opened the war by attacking Fort Sumter in 1861. A surge of nationalist outrage in the North fueled a long, intense American Civil War (1861-1865). It was fought largely in the South as the overwhelming material and manpower advantages of the North proved decisive in a long war. The war's result was restoration of the Union, the impoverishment of the South, and the abolition of slavery. In the Reconstruction era (1863–1877), legal and voting rights were extended to the freed slave. The national government emerged much stronger, and because of the Fourteenth Amendment, it gained the explicit duty to protect individual rights. However, when white Democrats regained their power in the South during the 1870s, often by paramilitary suppression of voting, they passed Jim Crow laws to maintain white supremacy, and new disfranchising constitutions that prevented most African Americans and many poor whites from voting, a situation that continued for decades until gains of the civil rights movement in the 1960s and passage of federal legislation to enforce constitutional rights.
The United States became the world's leading industrial power at the turn of the 20th century due to an outburst of entrepreneurship in the Northeast and Midwest and the arrival of millions of immigrant workers and farmers from Europe. The national railroad network was completed with the work of Chinese immigrants and large-scale mining and factories industrialized the Northeast and Midwest. Mass dissatisfaction with corruption, inefficiency and traditional politics stimulated the Progressive movement, from the 1890s to 1920s, which led to many social and political reforms. In 1920, the 19th Amendment to the Constitution guaranteed women's suffrage (right to vote). This followed the 16th and 17th amendments in 1913, which established the first national income tax and direct election of US senators to Congress. Initially neutral during World War I, the US declared war on Germany in 1917 and later funded the Allied victory the following year. After a prosperous decade in the 1920s, the Wall Street Crash of 1929 marked the onset of the decade-long world-wide Great Depression. Democratic President Franklin D. Roosevelt ended the Republican dominance of the White House and implemented his New Deal programs for relief, recovery, and reform. The New Deal, which defined modern American liberalism, included relief for the unemployed, support for farmers, Social Security and a minimum wage. After the Japanese attack on Pearl Harbor on December 7, 1941, the United States later entered World War II along with Britain, the Soviet Union, China, and the smaller Allies. The U.S. financed the Allied war effort and helped defeat Nazi Germany in Europe and defeated Imperial Japan in the Pacific War. The American use of newly inventedatomic bombs on Japanese cities remains controversial into the 21st century.
The United States and the Soviet Union emerged as rival superpowers after World War II. During the Cold War, the US and the USSR confronted each other indirectly in the arms race, the Space Race, proxy wars, and propaganda campaigns. US foreign policy during the Cold War was built around the support of Western Europe and Japan along with the policy of "containment" or stopping the spread of communism. The US joined the wars in Korea and Vietnam to try to stop its spread. In the 1960s, in large part due to the strength of the civil rights movement, another wave of social reforms were enacted by enforcing the constitutional rights of voting and freedom of movement to African-Americans and other racial minorities. Native American activism also rose. The Cold War ended when the Soviet Union officially dissolved in 1991, leaving the United States as the world's only superpower. As the 21st century began, international conflict centered around the Middle East following the September 11 attacks by Al-Qaeda on the United States in 2001. In 2008, the United States had its worst economic crisis since the Great Depression, which has been followed by slower than usual rates of economic growth during the 2010s.
