Now is probably the perfect time to pass
An article from June 2010 by Giovanni Peri of the University of California Davis found that increased immigration during a recovery creates jobs, leaves native employment unharmed in the short run, and in the long run increases productivity and average income.
This is an excellent time to revisit this paper, as the recovery has become robust and a bipartisan group of eight Senators have come together on an immigration reform package that will over time increase the number of immigrants and foreign nationals with visas working in the United States.
Here's a chart showing how — in the periods of rising immigration from 1994 to 2008 — the years with some of the highest immigration rates were also the years with the highest employment rate:
Even more, immigration means that native workers see increased employment. The study ran a regression and found the effects of an inflow of immigrants equal to 1 percent of the total workforce:
Since the inflow was an added 1 percent of immigrants to the workforce, any number greater than 1 means native workers gained jobs as a result of immigration. A number less than one indicates that some native jobs were lost.
Generally, the findings are that individual native workers are very slightly harmed initially, but enjoy robust benefits between four and seven years
However, looking in aggregate, the economy benefits immensely from immigration, as GDP per worker consistently was found to increase in both the short and long term.