The United States of America is a federal republic of fifty states, a federal district, and some territories. It is commonly called the United States (US, USA, U.S. or U.S.A.) and America. The country is mostly in central North America.
There are the forty-eight touching states and Washington, D.C., the capital district. These states are between the Pacific and Atlantic Oceans, bordered by Canada to the north and Mexico to the south. The state of Alaska is in the northwest of the continent, with Canada to its east and Russia to the west across the Bering Strait. The state of Hawaii is an archipelago in the mid-Pacific. The country also possesses some territories, or insular areas, in the Caribbean and Pacific. At 3.79 million square miles (9.83 million km2) and with about 306 million people, the United States is the third or fourth-largest country by total area and third-largest by land area and by population. The United States is one of the world’s most ethnically mixed and multicultural nations, the product of large-scale immigration from many countries.