Labor and Free Market Economics

Movement of workers from region to region, or country to country, is another important source of shifts in labor supply. When immigrants come to the United States, for instance, the supply of labor in the United States increases, and the supply of labor in the immigrants' home countries falls. In fact, much of the policy debate about immigration centers on its effect on labor supply and, thereby, equilibrium wages in the labor market. 

If workers from a poor rural region migrate to a relatively richer urban one, the smaller labor pool in the former will find equilibrium in the latter if interventionist policies are cast aside. Without intervention, that equilibrium can be reached as an over abundance of labor will result in unemployment, which in turn will drive some workers to other regions in need of labor. 

This is part of the reason that I believe doing away with immigration law and even international borders is a practical more solution. Beyond the failings of interventionist policies in politics and economics, restricting individuals from free migration is an affront to liberty, one typically maligned with special interests and using the labor force as pawns in the gaming of markets for profit where none is deserved. The resulting market inefficiencies are experienced as deadweight loss among other problems not able to be resolved through state economic manipulation. 

Source: 

Mankiw, N. G. (2007). Principles of microeconomics. (5th Edition ed.). Mason, OH: South-Western Cengage Learning.