Answer
Americans believed that the West was divinely enjoined to be part of the United States.
Step-by-step explanation:
Migration was an important factor in the development of America. The West attracted many peoples. Future generations looked at the borders of their settlements in the western crisis zones. A huge amount of land sold very cheaply or given away free of charge made it easier to set up a farm without worrying about initial debt.
So the unsuccessful and unemployed citizens takes this to escape from bad times and headed west, where there was cheap land, and even set up homesteads. Gold and other precious metals were discovered and that led some people there to gain wealth without hard work. The reservation system has been designed so that Native Americans stay away from land that European Americans would like to settle.
The eastern settlement was replaced by the Great Plain and the loss of the bison and growth affected in the number of white settlements. The arrival of Europeans on the continent affected the Midwest. But before that the American Indians were already started to occupy those western lands.