The National Academies reviewed the entire body of research and found little evidence that immigration meaningfully affects the employment of native-born workers, and a very small wage effect over the long run.

The definitive review is the National Academies of Sciences' The Economic and Fiscal Consequences of Immigration, a multi-year survey of the literature by a panel of economists. Its conclusions: there is little evidence that immigration significantly affects the overall employment levels of native-born workers, and measured over ten years or more, the effect on native wages overall is very small.

Where negative effects do show up, they land mostly on previous immigrants — the workers most substitutable for new arrivals — and on native-born workers without a high school diploma. That is a real cost borne by a real group, and it is an argument for a higher minimum wage, stronger unions and enforceable labor standards. It is not an argument that 6 million workers are the reason wages are flat.

The jobs themselves tell the story. Undocumented workers are 13.7 percent of construction and 12.7 percent of agriculture; in field crop work specifically, at least 40 percent of the labor force has been undocumented for thirty straight years. The top occupations are construction laborers, housekeepers, and cooks. These are not jobs being competed away from anyone — they are jobs that go unfilled at the offered wage when the workers are removed.

At the macro level the direction is not ambiguous. The Congressional Budget Office projected that the recent increase in immigration would add $8.9 trillion to GDP over a decade while reducing the federal deficit by roughly $900 billion.