The answer to this question is quite extensive, and it begins with understanding that as settlers began to farm the newly colonized lands beyond the East Coast, towards the West, there were several issues that torubled them.
First, there was lots of land to take from, but at a great expense, since farmers who settled far from the already civilized East Coast, were basically at the mercy of nature, Native Americans, and the resources they could procure for themselves.
Second, during the 1800´s, as the railroad systems began to expand, and new horizons to open up, small farmers also came to crash against the realities of industrialization and the growth of big businesses that were able to surpass them in production. This led to trouble as these smaller farmers were forced to seek ways to balance out the equation. As such, not only were they forced to adapt to whatever the railroad companies wanted to charge them to transport their products, but in order to compete, they had to start taking out loans from banks, which later they were not able to repay because sales for small farmers did not go as well, with the bigger businesses hugging the available markets.
Finally, the biggest problem that arose for these farmers was the issue that past the frontier, and near it, they were completely at the mercy of Native tribes, especially hostile ones, who would ravage farmers´ lands in order to push them out of their territories.
Another problem that must be noted is that with the expansion of the frontier, the fever for gold and silver also took people over, so that farmers had to face land issues not just with Native tribes, but also with settlers whose interests were different from agriculture.
These are only a few of the problems that were faced by settlers, especially farmers, as they settled the Western frontier.