What was the biggest obstacle in american western expansion?

The idea of manifest destiny simply stated it was america's destiny to expand from the atlantic ocean to the pacific. the word "destiny" implies an idea that it was within our rights as a nation to expand. in a paragraph of 125+ words, explain what could be wrong with that idea.

The 20th amendment, also called the lame duck amendment, decreased the amount of time between the presidential election and the inaugration of the new president. what are the advancements that allowed for this amendment?

Which event occurred in 1943 and to make the allied victory possible choose all answers that are correct