U.S. immigrant population (legal and illegal) reached 40 millions in 2010, the highest number in American history. Nearly 14 millions of new immigrants settled in the country from 2000 to 2010, making it the highest decade of immigration in American history. For the United States, the immigration has always been both crucial to the economic growth and a source of serious conflicts. There has been no significant movement toward federal immigration reform since bipartisan project blocked in 2007. But it has been the subject of fever legislation at a state level, and President Obama made a decision to return to this question in the coming presidential campaign.