The United States of America is a federal republic composed of 50 states, a federal district (Washington, D.C.), and several territories. The country is located in North America and is the world's third-largest country by total area. Its population is around 331 million people, making it the third most populous country in the world after China and India. The United States has a diverse economy that is based on free market principles. It is one of the world's largest economies, with a GDP of over $22 trillion. The country is a leadin…