The United States of America (also known as the United States, the United States of America or the United States of America) is a federal constitutional republic, which consists of fifty states and a federal district. The United States is mainly located in central North America. Its 48 states and the capital, Washington, D.C., lie between the Pacific Ocean and the Atlantic Ocean, bordering Canada in the north and Mexico in the south. Alaska is located in the northwest of the American continent, bordering Canada in the east and Russia across the Bering Strait in the west. Hawaii is an archipelago in the central Pacific Ocean. The country also owns several territories in the Caribbean and the Pacific Ocean.

With an area of 3.79 million square miles (9.83 million square kilometers) and a population of over 308 million, the United States is the third or fourth largest country in terms of total area and the third largest country in terms of land area and population. It is one of the countries with the most diverse races and cultures in the world, and it is the product of large-scale immigration from many countries. [6] The U.S. economy is the largest national economy in the world. It is estimated that the GDP in 20 10 is 14.799 trillion dollars (accounting for 23% of the nominal global GDP and 20% of the global GDP at purchasing power parity). [3][7]

Native Asians have lived in what is now the continental United States for thousands of years. After contact with Europeans, these native American populations were greatly reduced due to diseases and wars. The United States was founded by 13 British colonies located on the Atlantic coast. 1776 On July 4th, they issued the Declaration of Independence, proclaiming their right to self-determination and their right to establish cooperative alliances. In the American Revolution, the rebellious states defeated the British Empire, which was the first successful colonial war of independence. [8] The current Constitution of the United States was adopted on September 6, 17; The following year, its ratification made the states part of a single republic with a strong federal government. 179 1 approved the bill of rights consisting of ten constitutional amendments, which guaranteed many basic civil rights and freedoms.

In the19th century, the United States expelled indigenous tribes, acquired land from France, Spain, Britain, Mexico and Russia, and annexed the Republic of Texas and the Republic of Hawaii. The dispute over the expansion of slavery and the rights of States between the agriculture-oriented south and the industry-oriented north triggered the American Civil War in the1860s. The victory in the North prevented the permanent division of the country and led to the end of legal slavery in the United States. By AD1870s, the national economy was the largest in the world. [9] The Spanish-American War and World War I established the country's status as a military power. It became the first country to possess nuclear weapons and a permanent member of the United Nations Security Council in World War II. The end of the cold war and the disintegration of the Soviet Union made the United States the only superpower. The country accounts for 43% of global military expenditure and is a leading economic, political and cultural force in the world.