I'm sorry to say, but all these answers are incorrect. The real reason why was to escape poverty in other foreign countries. The immigrants moved to America for better opportunities and better jobs. When they arrived, they moved to places called tenements that were used for people to live in. But the downside was that EVERYONE was moving to America in the east where New York was and such, Causing Overpopulation. The Government had to resolve the issue By making the Homestead Act of 1862 signed by Abraham Lincoln, Which gave everyone the ability to move west for the first time. They thought it was their, "God Given Right" to explore the west due to the government giving them 162 acres FREE. But there was one problem that raised, But that's another question for next time.
Answer:
The 14th Amendment to the Constitution was ratified and granted citizenship to “all persons born or naturalized in the United States,” which included former slaves recently freed
