What are some of the conflicts surrounding immigration, population, and multiculturalism in the united states?

Immigration, Population, Multiculturalism and the competing interests of the American people:

For humanitarian concerns, the international community urges the American government to provide asylum to immigrants and those individuals and families who are seeking education and job opportunities.
However, for security concerns,some Americans believe that the government need to have stricter policies on accepting immigrants. Some extremists believe the country should not be taking in "outsiders" at all. On the contrary, some believe that multiculturalism is cultural narcissism and the recognition of cultures are politically motivated. 
This conflicts train more issues. It causes a lot of concern and debate because immigrants account for 27% of the U.S. population, 17% of which is part of the U.S. workforce. This reflects the statistic, cultural,  economic impact of immigrants to the citizenry.