http://www.factcheck.org/2010/05/doe...ion-cost-jobs/
Summary
Do immigrants take American jobs? It’s a common refrain among those who want to tighten limits on legal immigration and deny a "path to citizenship" — which they call "amnesty" — to the millions of immigrants living in the U.S. illegally. There’s even a new Reclaim American Jobs Caucus in the House, with at least 41 members.
But most economists and other experts say there’s little to support the claim. Study after study has shown that immigrants grow the economy, expanding demand for goods and services that the foreign-born workers and their families consume, and thereby creating jobs. There is even broad agreement among economists that while immigrants may push down wages for some, the overall effect is to increase average wages for American-born workers.
also:
But whether they’re legal, as in the CFAW ad, or illegal, as in our two other examples, really doesn’t matter for the purpose of answering our question: The truth is that immigrants don’t "take American jobs," according to most economists and others who have studied the issue.
Immigrant workers "create almost as many" jobs as they occupy, "and maybe more," said Madeleine Sumption, policy analyst at the nonpartisan Migration Policy Institute, which is funded by a range of foundations, corporations and international organizations. "They often create the jobs they work in." In addition, "they buy things, and they make the economy bigger," she told us. As she and a co-author wrote in a report last year for a group created by the British government:
Somerville and Sumption: [T]he impact of immigration [on a nation's economy] remains small, for several reasons. Immigrants are not competitive in many types of jobs, and hence are not direct substitutes for natives. Local employers increase demand for low-skilled labor in areas that receive low-skilled immigrant inflows. Immigrants contribute to demand for goods and services that they consume, in turn increasing the demand for labor. And immigrants contribute to labor market efficiency and long-term economic growth.