How did the expansion of united states territory redefinition of borders affect relationships with other nations (including native american tribes)?
what political conflicts took place due to this expansion?

War and the trail of tears for all five civilized tribes

The correct answer to this question is that those tribes that signed a treaty were given reserved lands while other nations like Mexico, Russia, Denmark, Spain, and others were paid. Thank you for posting your question. I hope that this answer helped you. Let me know if you need more help. 

The transcontinental railroad provided a means of fast transportation. it cut a 6 month trip into 6 days, created jobs for many people and encouraged immigration. the homestead act played a huge role in western expansion; it allowed settlers to begin a fresh start, and gave them land in exchange for their residence for up to five years and a small fee.