The major factors that caused people to want to move west were economic and social. These two types of factors were closely related.
Economically, people wanted more opportunities. During this time, America was a mainly agrarian economy and the West had land that was free or very cheap. By moving West, people could get a much better opportunity to prosper.
Socially, people wanted more freedom and autonomy. Moving West was seen (especially in colonial days) as a way of getting away from the control of the upper classes. So moving west was seen as a way of asserting independence.
Both of these helped influence people to move west.
A factor that should be first mentioned is that Britain initially tried to prevent the citizens of America from expanding past the Appalachian Mountains (Proclamation of 1763). Following the Revolutionary War and having won their independence from Britain, the Americans decided to build their nation. They had already explored and settled the East and this left them to move in the Westward direction. Territorial expansionism was favored by Thomas Jefferson and who had a strong voice in early government. The United Sates was hungry for ownership of more land. After the purchase of Louisiana from France, Clark and Lewis were sent on a mission to chart the properties that had been purchased and to explore the resources, available waterways for transportation, and persons in the lands beyond Louisiana.
The United States had become heavily populated in regions of the North and larger cities. There had been talk of the lands beyond and what resources that could be provided. Rapid expansion, population increase, and production had occurred in the larger cities particularly up North. Transportation costs had become cheaper and more and more immigrants were entering and settling in America. The need for more land was becoming evident to the government. With the opening of new territories and the promise of cheap land, people began to move westward in search of their destiny. Other factors that influenced the move included freedom of religion and the right to live and practice the religion of choice led to some of the population moving westward away from British/protestant control. Person’s desiring to practice their own beliefs or in social/religious groups sought out land s away from the stifling guidance of the protestants.