Having a minimum wage is what makes ‘illegal immigration’ feasible. Most illegal immigrants are unskilled, poorly paid workers; Epstein & Hezler (2013) say that “Minimum wages play an essential role since they put a limit on local workers’ and legal migrants’ wages. Thus, under certain circumstances, the probability of employing illegal workers is increased.” Incidentally, the authors also suggested that one way to reduce illegal immigration would be to increase legal immigration (assuming a constant minimum wage). According to a survey commissioned by the Migration Observatory at the University of Oxford, “Among respondents who want immigration reduced overall, 54% said that they would like reductions either “only” (28%) or “mostly” (26%) among illegal immigrants”.
Illegal immigrants fill a gap for employers who cannot survive by hiring people at or above the minimum wage and who also cannot attract legal residents that are willing to break the law and work for less than minimum wage. Firstly, if there were no minimum wage, then employers would have less incentive to employ illegal immigrants and would, instead, turn to legal residents to offer their labour for these rates. This would simultaneously empower the unemployed with more opportunities to offer their labour, make entrepreneurship increasingly feasible (especially that of the labour-intensive variety) and significantly reduce illegal immigration.
Whether the contempt toward illegal immigrants is from allegations of criminal activity, taking jobs, etc., this has a spill over effect on the perceptions of immigrants in general. There is an oft-documented tendency for people to stereotype and make sweeping generalisations (even if we are subsequently ashamed of doing so). Hence, any negative perceptions of illegal immigrants contribute to the general degradation of legal immigrants’ status in society.
Furthermore, and perhaps most importantly (depending on who you are), via a combination of both the inflexibility of the labour markets that it contributes toward (and, therefore, of price levels in various other markets) and the controversial illegal immigration that it makes feasible, the minimum wage is one of the greatest barriers to the possibility of free immigration and, therefore, of a world where greater understanding and co-operation between people flourishes.