Immigrants are willing to do the jobs that Americans won't do, for wages that American's would not accept. They take the jobs that Americans don't want.
I believe the answer is: one-fourth of all new businesses are started by immigrants
For example, Google, which arguably the largest tech company in the world today, was co-founded by a russian Immigrant named Sergey Brin. People in some media like to focus on how immigrants affect the availability of low-skilled labour because it most likely give the most support from the supporters of a certain political party.
