In American history, a pioneer is any of the people who migrated west to join in settling and developing new areas, especially those who settled any territory previously unsettled or undeveloped by European or American society. Though most of us think of pioneers strictly in terms of those who came to the "West", the earliest pioneers settled areas now considered the "East".
The first westward migrations occurred as representatives of the Thirteen Colonies sought to open up new lands for their respective colonies westward. Those whose original royal charters did not specify a western limit simply extended their lands directly and indefinitely westward. After the United States was formed upon the ratification of the U.S. Constitution, federal coordination and legislation began to give settlement a more unified approach.
As western settlement grew, common details emerged. Most pioneers traveled in wagon trains, groups of wagons containing settlers and their families. They banded together for common defense and to combine their efforts. Pioneers in the East often had to clear the land, owing to lush forests there. In the Midwest, the task was to bring agricultural fertility to the Great Plains.
The figure of the pioneer has played a large role in American culture and literature. While much cultural note is also given to other figures of a more transient nature, such as cowboys, trappers prospectors, miners, etc., the pioneer alone represents those who went into unexplored territory in search of a new life, looking to establish permanent settlement.