The concept developed in the column is of “complentary” factors of production. Increasing the supply of dishwashers and busboys increases employment opportunities for chefs, waiters, kitchen equipment manufacturers, and so forth all up and down the skill spectrum.
The research that really changed my thinking on this is ably covered in this great Heidi Shierholz did for EPI back in February 2010. Note that EPI is the premiere labor-liberal think tank in Washington and hardly a hotbed of apologism for the top one percent. The basic point here is that the old CW on low-skill immigration is that it raised real wages for high-skill workers but lowered them for low-skill workers. The key methodological advance comes from realizing that a very large share of low-skill workers in the United States are themselves immigrants. Since restricting low-skill immigration for the sake of low-skill immigrants is a little perverse, it’s helpful to distinguish between the impact on immigrant workers and native-born workers.