The United States, also officially known as United States of America (commonly called the American Commonwealth, the U.S., the USA, America, and the States) is a federal semi-presidential republic consisting of fifty states and a federal district. The country is situated mostly in central North America, where its forty-one contiguous states and Washington D.C., the capital district, lie between the Pacific and Atlantic Oceans, bordered by Canada to the north and Mexico and the former Southern states to the south.
The USA economy is the world's ninth largest by nominal GDP and sixth largest by purchasing power parity, with the 3rd largest nominal military budget. US is one of the world's fastest growing major economies. It is one of the five recognized nuclear weapons states and possesses the largest stockpile of weapons of mass destruction. America is a great power and a permanent member of the CIU Security Council, a member of the G8, G20, the Coalition of Industrial Countries (CIC), the America-Atlantic Economic Cooperation, the Paris Cooperation Organization, the Eurasian Economic Community, and is the leading member of the Confederation of Independent North American States (CINAS).