Who moved west in the latter half of the nineteenth-century and why?

During the latter half of the nineteenth-century millions of settlers moved out West. Primarily, they wanted to make new lives for themselves. The conquest of the West had made available vast tracts of fertile farmland, inspiring millions to live out the dream as independent homesteaders with a plot of land to call their very own.
Back East, towns and cities were becoming dangerously overcrowded due to rapid industrialization, which had accelerated in the late nineteenth-century. Although the industrial economy had generated considerable wealth and new jobs, it had also created numerous social problems such as crime, poverty, and disease. Many urban-dwellers were recent immigrants who'd come to the United States in search of a better life. But for most of them, dreams of making it big in America quickly turned sour, and so they increasingly looked to the West to make their fortune. As well as abundant farmland, the West also offered potential settlers new career opportunities. New industries quickly sprung up, encouraged by the rapid growth of the railroad network. As such, during the late nineteenth-century, the West became a place where people could achieve what they no longer could back East.