Immigration

     I think in all respects that immigration had a very positive respect on American culture.  If you think about it, American isn't even an ethinicity; it's merely whre you were born. America is a mix of cultures put together.  Because of this, immigration is merely an increase in the number of citizens, not an induction to a new culture.  America is the home of the free, and is not exposed to any one culture because of this diversity.

The positives:
 We increased our population, which makes us more intimidating as a country.  It added some largely needed diversity.

The negatives:

  Our country a higher deamnd for jobs, meaning that we could afford to be bad to workers, meaning that while we had a higher export, we became unfair and racist to many cultures, which can be bad in such a diverse people.