in a short paragraph, describe the factors that contributed to America's westward expansion during the 1800s.

Factors that contributed to America's westward expansion in the later half of the 19th century included the quelling of Native American resistance and relocation of tribes to reservations, gold rushes, in Colorado, California, and the Black Hills of South Dakota, and the building of the Intercontinental Railroad

Explanation:

a big wall across the mexican border so no drugs, terrorist, or illegal immigrants can come through : )    

the real answer is b