United States of America USA

The United States of America USA., Commonly known as the United States (US) or America, is a federal republic consisting of 50 states and a federal district. The 48 contiguous states and Washington, DC, are at the center of North America between Canada and Mexico. The state of Alaska is located in the northwestern part of North America and the state of Hawaii is an archipelago in the central Pacific. The country also has five populated and numerous uninhabited territories in the Pacific and Caribbean. At 3.80 million square miles (9.85 million km2) and with over 320 million people, the United States is the world's fourth largest by total area and the third most populous country. It is one of the most ethnically diverse and multicultural countries in the world, the product of large-scale immigration from many countries. The geography and climate of the United States are also very diverse, and the country is home to a variety of wildlife.Paleo-Indians migrated from Eurasia to what is now the continental United States about 15,000 years ago, with European colonization began in the 16th century The United States emerged from 13 British colonies located along the east coast. Disputes between Britain and the colonies led to the American Revolution. On July 4, 1776, as the colonies fought Britain in the American Revolutionary War, the delegates of the 13 colonies unanimously approved the Declaration of Independence. The war ended in 1783 with the recognition of the independence of the United States by the Kingdom of Great Britain and was the first successful war for independence from European colonial empire. The country's Constitution was adopted on September 17, 1787 and ratified by the States in 1788. The first ten amendments, collectively called the Bill of Rights, were ratified in 1791 and designed to ensure many fundamental civil rights and freedoms.Powered by the doctrine of Manifest Destiny, the United States embarked on a vigorous expansion in North America throughout the 19th century This involved the displacement of Native American tribes, the acquisition of new territories, and gradually admitting new states, until 1848 the nation swept the continent. During the second half of the 19th century, the American Civil War ended legal slavery in the country. Later that century, the United States spread to the Pacific Ocean, and its economy, driven largely by the industrial revolution began to rise. The Spanish-American War and World War I confirmed the country's status as a global military power. The United States emerged from World War II as a global "superpower", the first country to develop nuclear weapons, the only country to use in the war, and as a permanent member of the United Nations Security Council. The end of the Cold War and the dissolution of the Soviet Union left the United States as the sole superpower in the world.The United States is a developed country and has largest national economy in the world, benefiting from an abundance of natural resources and the high productivity of workers. While the US economy is considered post-industrial, the country remains one of the largest manufacturers in the world. Representing 37% of global military spending and 19% of global GDP (PPP), which is the foremost world power economic and military, a prominent political and cultural force, and a leader in scientific research and technological innovation .