The economy and illegal immigration

I came across a study published by the Missouri Budget Project in June examining the impact of illegal immigrants on the Missouri economy. Given the scarcity of exact figures, the numbers must be estimated.

The study concludes that illegal immigrants generate $29 to $57 million in taxes. In terms of services, many of the major social services, food stamps and medicaid are unavailable to illegal immigrants (though their children may be eligible). The study did estimate the cost of schooling, approximately $17.5 to $36.2 million.

One aspect they didn't examine was the effect undocumented workers have on wages, economist and New York Times columnist Paul Krugman examined the issue in March and found that illegal immigration does depress wages. Enough to offset tax revenue?

Update: Reader Clark points to an article in the New York Times summarizing studies that say the impact of illegal immigration on wages is less than expected. Other economic forces have muted the impact of illegal immigration on the labor market. Some businesses have expanded and others have stayed in the U.S. rather than leave in search of cheaper labor.

Even the authors of the study that Krugman cites have said that their article does not take into account a number of economic forces. When included, they said, their own estimates are reduced by half, if not more.