The United States of America (commonly referred to as the United States, the U.S., the USA, or America) is a federal constitutional republic comprising fifty states and a federal district. The country is situated mostly in central North America, where its 48 contiguous states and Washington, D.C., the capital district, lie 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 several 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 diverse and multicultural nations, the product of large-scale immigration from many countries. The U.S. economy is the largest national economy in the world, with an estimated 2008 gross domestic product (GDP) of US $14.3 trillion (23% of the world total based on nominal GDP and almost 21% at purchasing power parity).
The total land area of the contiguous United States is approximately 1.9 billion acres. Alaska, separated from the contiguous United States by Canada, is the largest state at 365 million acres. Hawaii, occupying an archipelago in the central Pacific, southwest of North America, has just over 4 million acres. After Russia and Canada, the United States is the world's third or fourth largest nation by total area, ranking just above or below China. The ranking varies depending on how two territories disputed by China and India are counted and how the total size of the United States is calculated: the CIA World Factbook gives 3,794,083 sq mi (9,826,630 km2), the United Nations Statistics Division gives 3,717,813 sq mi (9,629,091 km2), and the Encyclopedia Britannica gives 3,676,486 sq mi (9,522,055 km2). Including only land area, the United States is third in size behind Russia and China, just ahead of Canada. |
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