Philip Klein has a short piece in the dead-tree version of The American Spectator making a point 
similar to my own about population growth leading to bigger government (though he was making a point about socialized medicine). He writes that “the more people there are in a given area, the more likely it is that people will come into conflict, and the less likely that they will treat each other with basic decency.” And therefore the more regulations you’ll need, and more regulators to implement the regulations, and more laws to authorize the regulations, and more lawmakers to make the laws, and more legislative staff to write the laws, and more lobbyists to influence the laws. Thus does a libertarian approach to immigration lead to a bigger and bigger state.