The United States of America (hereinafter referred to as the United States) is a federal constitutional country, which consists of Washington, D.C., 50 states, Guam and many other overseas territories. Its main part is located in central North America. The original versions of CIA world surveys 1989 to 1996 listed the total area of the United States as 93726 10 square kilometers? 1997 was revised to 9.63 million square kilometers (plus the Great Lakes and coastal waters such as estuaries, harbors and inland seas under the sovereignty of the United States) with a population of 320 million. It is an immigrant country with a common English.