About USA

The United States of America (USA), is a federal republic consisting of 50 states and a federal district. The 48 contiguous states and Washington, D.C., are in central North America between Canada and Mexico. 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 country by total area and third most populous. It is one of the world's most ethnically diverse and multicultural nations.
European colonization beginning in the 16th century. The United States emerged from 13 British colonies located along the East Coast. Disputes between Great Britain and the colonies led to the American Revolution. On July 4, 1776, as the colonies were fighting Great Britain in the American Revolutionary War, delegates from the 13 colonies unanimously adopted the Declaration of Independence. The war ended in 1783 with recognition of the independence of the United States by the Kingdom of Great Britain.
During the second half of the 19th century, the American Civil War ended legal slavery in the country. By the end of that century, the United States extended into the Pacific Ocean, and its economy, driven in large part by the Industrial Revolution, began to soar. 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 them in warfare, 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 world's sole superpower.
The United States is a developed country and has the world's largest economy, benefiting from an abundance of natural resources and high worker productivity. While the U.S. economy is considered post-industrial, the country continues to be one of the world's largest manufacturers.