What factor triggered the largest wave of migration to the west?

In the late 1800s, people in many parts of the world decided to leave their homes and immigrate to the United States. They were fleeing crop failure, land and job shortages, rising taxes, and famine, and many people came to the      U. S. because it was perceived as the land of economic opportunity. Hope that helped! :)

Sponge bob ate the crab