This week, Washington Post columnist Robert Samuelson set forth the claim that the United States is Importing Poverty. In it, he argues that immigration has increased poverty in the U.S. because the hispanics who disproportionately migrate here also happen to fall disproportionally below the poverty line. A number of critics could easily read this article to mean that we should cut off immigration, but that would just be another way to lie with statistics.
I would pose the question this way: What impact does immigration have on (1) The immigrants who come here; (2) Those currently at or near the poverty line in the U.S., and; (3) Those living in poverty in Mexico.
The first group are almost unambiguously better off. Otherwise, why give up the life you lead in Mexico, Guatemala, or elsewhere? Although immigrants often earn less and work harder than their native cohort in the U.S., they are glad to be "exploited" in this sense so that they can use some of their repatriated savings to purchase land or improve the lives of their families in their home country.
The third group is also usually better off. For the most part, the emigration of moderately-skilled hispanics to the United Statess, along with the FDI attracted by the relative abundance of unskilled labor, has tended to increase wages. And that's before accounting for the impact of repatriated wealth from emigrant family members.
The tricky middle is the second group. There is some evidence that immigration has worsened wages in the labor market for the least-skilled and least-experienced U.S. natives. But, at the same time immigration has tended to leave all other groups' welfare unchanged or improved.
To me, the argument comes down to how, not if we show concern for those who are poor. I would argue that if we are concerned with poverty, we should not just be concerned with the absolute headcount below some artificial poverty line, but also with the severity of the poverty that those folks live in. In addition, if our intentions are altruistic (and not just "us against them"), we should be concerned with those living in the most abject of poverty conditions, not just those living here, and the most poor folks out there are generally living outside our (increasingly gated) borders. I would only weigh those small losses to our own citizens against the huge gains to those who would come here and not treat them as One Fifth of One American.