The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territories, 326 Indian reservations, and nine minor outlying islands. It is the world’s third-largest country by both land and total area. The United States shares land borders with Canada to the north and with Mexico to the south as well as maritime borders with the Bahamas, Cuba, and Russia, among others. With more than 331 million people, it is the third most populous country in the world. The national capital is Washington, D.C., and the most populous city and financial center is New York City.
Paleo-Indians migrated from Siberia to the North American mainland at least 12,000 years ago, and European colonization began in the 16th century. The United States emerged from the Thirteen British Colonies established along the East Coast. Disputes with Great Britain over taxation and political representation led to the American Revolutionary War (1775–1783), which established the nation’s independence. In the late 18th century, the U.S. began expanding across North America, gradually obtaining new territories, sometimes through war, frequently displacing Native Americans, and admitting new states. This was strongly related to belief in manifest destiny, and by 1848, the United States spanned the continent from east to west. Slavery was legal in the southern United States until 1865, when the American Civil War led to its abolition. A century later, the civil rights movement led to legislation outlawing racial discrimination against African Americans. The Spanish–American War and World War I established the U.S. as a world power, and the aftermath of World War II left the United States and the Soviet Union as the world’s two superpowers. During the Cold War, both countries opposed each other in the Korean and Vietnam Wars but avoided direct military conflict. They also competed in the Space Race, which culminated in the 1969 American spaceflight that first landed humans on the Moon. The Soviet Union’s dissolution in 1991 ended the Cold War, leaving the United States as the world’s sole superpower.
The United States is a federal republic with three separate branches of government, including a bicameral legislature. It is a founding member of the United Nations, World Bank, International Monetary Fund, Organization of American States, NATO, and other international organizations. It is a permanent member of the United Nations Security Council. Considered a melting pot of cultures and ethnicities, its population has been profoundly shaped by centuries of immigration. The United States is a liberal democracy; it ranks high in international measures of economic freedom, quality of life, education, and human rights; and it has low levels of perceived corruption. It lacks universal health care, retains capital punishment, and has high levels of incarceration and inequality.
The United States is a highly developed country, and its economy accounts for approximately a quarter of global GDP and is the world’s largest by GDP at market exchange rates. By value, the United States is the world’s largest importer and second-largest exporter. Although its population is only about 4.2% of the world’s total, it holds over 30% of the total wealth in the world, the largest share held by any country. Making up more than a third of global military spending, it is the foremost military power in the world and a leading political, cultural, and scientific force.
The 1930s was defined by a global economic and political crisis that culminated in the Second World War. It saw the collapse of the international financial system, beginning with the Wall Street Crash of 1929, the largest stock market crash in American history. The subsequent economic downfall, called the Great Depression, had traumatic social effects worldwide, leading to widespread poverty and unemployment, especially in the economic superpower of the United States and in Germany, which was already struggling with the payment of reparations for the First World War. The Dust Bowl in the United States (which led to the nickname the “Dirty Thirties”) exacerbated the scarcity of wealth. U.S. President Franklin D. Roosevelt, elected in 1933, introduced a program of broad-scale social reforms and stimulus plans called the New Deal in response to the crisis.
In the wake of the Depression, the decade also saw the rapid retreat of liberal democracy as authoritarian regimes emerged in countries across Europe and South America, including Italy, Spain, and in particular Nazi Germany. With the rise of Adolf Hitler, Germany undertook a series of annexations and aggressions against neighboring territories in Central Europe, and imposed a series of laws which discriminated against Jews and other ethnic minorities. Weaker states such as Ethiopia, China, and Poland were invaded by expansionist world powers, with the last of these attacks leading to the outbreak of World War II on September 1, 1939, despite calls from the League of Nations for worldwide peace. World War II helped end the Great Depression when governments spent money for the war effort. The 1930s also saw many important developments in science and a proliferation of new technologies, especially in the fields of intercontinental aviation, radio, and film. (Wikipedia)