In addition to talking about the roots of the Mormon Church's stance on immigration, Walker Wright also has this to say about the economic and cultural costs and benefits of immigration: 

A 2011 meta-analysis by economist Michael Clemens found that dropping all current immigration restrictions would result in a doubling of world GDP. A more recent analysiscorroborated these findings, concluding that lifting all migration restrictions would increase world output by 126 percent. Similarly, a 2013 study found that dropping all immigration barriers would result in an additional income of $10,798 per worker (migrant and non-migrant alike); doubling the income of the world’s most deprived.

Despite these economic benefits, many rich country natives worry that an overabundance of immigrants will make things worse. Some accuse immigrants of stealing native jobs, depressing native wages, undermining native culture and institutions, bloating the welfare state, and/or being criminals and terrorists. The vast majority of empirical studies, however, contradicts these arguments. Several large literature reviews — including two from the National Academy of Sciences and one from Oxford University — find that the long-term effects of immigration on jobs, wages and the fiscal budget tend to be neutral to slightly positive. Immigrants also assimilate rather well into their host countries and even appear to boost the economic freedom of their institutions.

On my own views on immigration, see these two posts:

• "The Hunger Games" Is Hardly Our Future--It's Already Here
• Us and Them

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