Why was a wave of immigration from Northern Europe to the United States?

Due to various reasons

Explanation:

The United States saw immigration due to various reasons. The major reason was economic where people moved due to better earning opportunities. The other major reason was religious freedom that compelled alot of people to move. There were other immigrants, mainly Africans who were slaves and moved against their will.

From northern and western Europe in the 19th century, a-lot of people migrated due to famine in their native countries.