<Tr> <Th> Internet TLD </Th> <Td>. us </Td> </Tr> <Tr> <Td_colspan="2"> Website usa.gov </Td> </Tr> <P> The United States of America (USA), commonly known as the United States (U.S.) or America (/ əˈmɛrɪkə /), is a federal republic composed of 50 states, a federal district, five major self - governing territories, and various possessions . Forty - eight states and the federal district are contiguous and located in North America between Canada and Mexico . The state of Alaska is in the northwest corner of North America, bordered by Canada to the east and across the Bering Strait from Russia to the west . The state of Hawaii is an archipelago in the mid-Pacific Ocean . The U.S. territories are scattered about the Pacific Ocean and the Caribbean Sea, stretching across nine official time zones . The extremely diverse geography, climate and wildlife of the United States make it one of the world's 17 megadiverse countries . </P> <P> At 3.8 million square miles (9.8 million km) and with over 324 million people, the United States is the world's third - or fourth - largest country by total area and the third-most populous . The capital is Washington, D.C., and the largest city is New York City; twelve other major metropolitan areas--each with at least 4.5 million inhabitants--are Los Angeles, Chicago, Dallas, Houston, Washington, D.C., Philadelphia, Miami, Atlanta, Boston, San Francisco, Phoenix, and Riverside--San Bernardino . </P>

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