So Boys and Girls.... What's the reason for the Arizona law?
Is it because the crime rate is to low? [News flash: Crime rates and prison incarceration among legal and illegal aliens is lower (actually MUCH lower) than among the native population.]
"The problem of crime in the United States is not “caused” or even aggravated by immigrants, regardless of their legal status. This is hardly surprising since immigrants come to the United States to pursue economic and educational opportunities not available in their home countries and to build better lives for themselves and their families. As a result, they have little to gain and much to lose by breaking the law. Undocumented immigrants in particular have even more reason to not run afoul of the law given the risk of deportation that their lack of legal status entails." -source and source
Is it because immigrants both illegal and legal are an economic burden for natives? Is it because they use services they can't and don't pay for causing hardships for citizens?
Immigrants, both legal and illegal, pay taxes. They get jobs, they seek education, they add to the cultural richness of society, and they help the economy. The benefits to the economies of the states with high immigrant populations is at worst a wash at best a pretty good benefit. The relatively small price, economically, of immigration just doesn't support the level of caterwauling coming from the opponents of immigration reform. Finally, it's just a myth that immigrants take jobs away from natives. You can check the "small price" link for that one too. In this case, mythically true = statistically insignificant.
Is it because some folks feel threatened by the rise of the new immigrant population and that they have much invested and therefore much to lose in terms of status, privilege and wealth?