The correct answer to this open question is the following.
The challenges of settling the country west of the Mississippi were basically that the land west of the Mississippi was not for farming because the soil was not as fertile as in the regions of the East. The land west of the Mississippi had no trees at all and there were mountain ranges. There was a large zone of plains so farmers could not have enough water or timber as the used to have in the East. People had to resolve many issues about living west the Mississippi and that required to face some challenges.
