The United States of America (USA or USA), commonly known as the United States of America (USA or US) or the United States, is a country located primarily in North America. It consists of 50 states, 1 federal district, 5 major non-corporate territories, 326 Indian territories and 9 small remote islands. With approximately 3.8 million square miles (9.8 million square kilometers), it is the fourth largest country in the world in terms of land area and is the third largest in total area. The United States shares a land border with Canada in the north and Mexico in the south, and has maritime borders with Bahama, Cuba, Russia, and so on. The United States, with a population of over 331 million, is ranked number three in the world in terms of population. The state capital is Washington, D.C., and the most populous city and commercial center is New York City.