United States of America

According to Dictionary.com, the United States of America is "...a republic in the North Western Hemisphere

comprising 48 conterminous states, the District of Columbia, and Alaska in North America, and Hawaii in the North Pacific."

Early History and Spanish (1492-1821)
The territory represented by the continental United States had, of course, been discovered, perhaps several times, before the Spanish voyages of Christopher Columbus. When Columbus arrived, he found the New World inhabited by peoples who in all likelihood had originally come from the continent of Asia. Probably these first inhabitants had arrived 20,000 to 35,000 years before in a series of migrations from Asia to North America by way of the Bering Strait. By the time the first Europeans appeared, the indigenous people (commonly referred to as Indians) had spread and occupied all portions of the New World.

English Colonization and Independence (1606-1776)
Following the first voyage of Christopher Columbus in 1492, Spain and Portugal established colonies in the New World, beginning the European colonization of the Americas. France and England, the two other major powers of 15th-century Western Europe, employed explorers soon after the return of Columbus's first voyage. In 1497, King Henry VII of England dispatched an expedition led by John Cabot to explore the coast of North America, but the lack of precious metals or other riches discouraged both the Spanish and English from permanently settling in North America during the early 16th century.

In 1606, King James I of England granted charters to both the Plymouth Company and the London Company for the purpose of establishing permanent settlements in North America. In 1607, the London Company established a permanent colony at Jamestown on the Chesapeake Bay, but the Plymouth Company's Popham Colony proved short-lived. The colonists at Jamestown faced extreme adversity, and by 1617 there were only 351 survivors out of the 1700 colonists who had been transported to Jamestown. After the Virginians discovered the profitability of growing tobacco, the settlement's population boomed from 400 settlers in 1617 to 1240 settlers in 1622.

Following the success of the Jamestown and Plymouth Colonies, several more English groups established colonies in the region that became known as New England. In 1629, another group of Puritans led by John Winthrop established the Massachusetts Bay Colony, and by 1635 roughly ten thousand English settlers lived in the region between the Connecticut River and the Kennebec River. Eventually, the British had thirteen colonies in the New World, which would later seek independence, resulting in the United States of America.

Opinion for independence swept the colonies in the spring of 1776. The Congress recommended that colonies form their own governments and assigned a committee to draft a declaration of independence.

Westward Expansion (1803-1909)
The Louisiana Purchase of 1803 intensified American Migration to the west that was already well underway. Anglo-American settlement in the 18th century had largely been confined to the eastern seaboard. It made its boldest inroads where rivers allowed easy internal transportation. As a result the chief population centers of early North America were clustered on the coast or along its major inland waterways.

In 1790 the fast-growing population of the United States was 3.9 million, but only 5% of Americans lived west of the Appalachian Mountains that run from Maine to Georgia. By 1820, however, the total U.S. population had already reached 9.6 million and fully 25 percent of them lived west of the Appalachians in nine new states and three territories.