About U.S.A

 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, nine small outlying islands and 326 Indian reservations. It is the third largest country in the world both by land and total area. [d] The United States shares land borders with Canada to the north and Mexico to the south. It shares maritime borders with the Bahamas, Cuba, Russia and other nations.With more than 333 million inhabitants, it is the most populous country in the Americas and the third most populous in the world. The state capital is Washington, DC and the most populous city and financial center is New York City.

Paleoamericans migrated from Siberia to the North American mainland at least 12,000 years ago, and later advanced cultures began to emerge. These advanced cultures had almost completely declined by the time Europeans arrived in North America and began colonizing the continent. The United States emerged from thirteen British colonies when disputes with the British crown over taxation and political representation led to the American Revolution (1765–1791), which created the nation's independence. In the late 18th century, the US began to expand across North America, gradually acquiring new territories, sometimes through war, often displacing Native Americans and accepting new states. In 1848, the United States spanned the continent from east to west. Controversy surrounding the practice of slavery culminated in the secession of the Confederate States of America, which fought the remaining states of the Union during the American Civil War (1861–1865). With the victory and preservation of the Union, slavery was abolished by the Thirteenth Amendment.

By 1900, the United States had become the world's largest economy, and the Spanish-American War and World War I established the country as a world power. After the surprise Japanese attack on Pearl Harbor in 1941, the US entered World War II on the side of the Allies. The aftermath of the war left the United States and the Soviet Union as the world's two superpowers. During the Cold War, the two countries engaged in a struggle for ideological supremacy, but avoided direct military conflict. They also competed in the Space Race, which culminated in the 1969 US space flight that landed humans on the moon for the first time. At the same time, the civil rights movement (1954–1968) led to legislation repealing state and local Jim Crow laws and other codified racial discrimination against African Americans. The collapse of the Soviet Union in 1991 ended the Cold War, leaving the United States as the world's sole superpower. The 9/11 attacks in 2001 led the United States to launch the War on Terror, which included the War in Afghanistan (2001–2021) and the War in Iraq (2003–2011).

The United States of America is a federal republic with three separate branches of government, including a bicameral legislature. It is a liberal democracy and a market economy; ranks first in international indicators of human rights, quality of life, income and wealth, economic competitiveness and education; and has a low level of perceived corruption. It has high rates of incarceration and inequality, allows for the death penalty, and lacks universal health care. As a melting pot of cultures and ethnicities, the US has been shaped by centuries of immigration.

The United States is a highly developed country, and its economy accounts for about a quarter of global GDP and is the largest in the world by GDP at market exchange rates. By value, the United States is the world's largest importer and second largest exporter. Although the US makes up just over 4.2% of the world's total population, the US holds over 30% of the world's total wealth, the largest share held by any country. The United States of America is a founding member of the United Nations, the World Bank, the International Monetary Fund, the Organization of American States, NATO, and is a permanent member of the UN Security Council. The country accounts for more than a third of global military spending and is the world's leading military power and a leading political, cultural and scientific force.