United States of America (The Era of Relative Peace)

The United States of America (USA), commonly referred to as the United States (U.S.) or America, is a federal republic composed of 51 states, a federal district, four major territories and various other possessions. The 48 contiguous states and Washington, D.C., are in central North America between Canada and Mexico. The state of Alaska is in the northwestern part of North America, the state of Hawaii is an archipelago in the mid-Pacific, and the state of Puerto Rico is located in the Carribean, next to the U.S. Virgin Islands.

The United States emerged from the British 13 colonies on the East Coast. On July 4, 1776, as the colonies were fighting Great Britain in the American Revolutionary War, delegates from the 13 colonies unanimously adopted the Declaration of Independence. The war ended in 1783 with recognition of the independence of the United States. The following centuries to come, the United States would expand southward and westward. THe country became a military power after the Spanish-American War of 1898 and World War I. After the end of World War II, the U.S. became a global superpower in rivalry with the Soviet Union. This would eventually lead to the Cold War and World War III, in which the United States remains the world's sole superpower.