What were the challenges of setting the country west of the mississippi?

There were many challenges of western immigration in the US. Despite how much it's romanticized in modern times. : (

The prevalent problems the pioneers heading west faced were ones concerning exposure, starvation, sickness and dangerous environments.

Oxen often died of thirst, the wagons were often overloaded and infections and sicknesses were very common. In addition to the above, the trails westwards were poorly marked, causing travellers to lose their way. One such instance was the infamous Donner Party, who followed an unreliable guide west and were so hopelessly lost that they became stranded in the Sierra mountains, where many died at the hands of their fellow travellers.

There were also the financial problems. Oxen and wagons were expensive, and in order to afford it, families had to leave behind friends, family, businesses and belongings in the hopes of new opportunity in the west.

Good luck in your studies!