Immigration affected both immigrants and americans in many ways.
Assuming you are talking about the 1900s and onward:
Positive:
- Larger population may mean larger income source for governments, which can then provide more benefits for the citizens.
- etc.
Negatives:
- Larger populations means that less jobs are available to native US citizens and others. Also, when immigrants are more willing to work for less, it angers the citizens, as they think that their jobs are being taken away.
