For the uninitiated they together led to the formation of a very interesting stream of Economics – Public Choice Theory
In particular, it studies the behavior of voters, politicians, and government officials as (mostly) self-interested agents and their interactions in the social system either as such or under alternative constitutional rules.
Buchanan given another view on migration:
If you have an area where high-income receivers concentrate, you have a higher fiscal capacity. That fiscal capacity is a valuable resource and will create rent-seeking. People will trying to get that resource one way or the other, including immigration. It is very much like the medieval peasants putting their sheep on the commons pasture. It is better than the open range, and if you let them have open access they will, in fact, put too many sheep on the pasture and waste the value that the pasture has. We want to limit the exploitation of the fiscal capacity of the richer regions by keeping down the rate of immigration to a level that would be meaningful and efficient. One way to do that is to have a scheme of equalization which essential bribes people to stay in the poorer regions.