The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or simply America, is a sovereign country located mostly within North America and is divided up into 50 states. The United States shares land borders with Canada to its north, and with Mexico to its south. The country also possesses territories, and insular areas, in the Caribbean and Pacific. With a population of over 331 million, it is the third most populous country in the world. The national capital is Washington, D.C., and the most populous city and financial center is New York City.