A common argument against returning to the immigration policy of 1790-1875, where virtually anybody in the world could immigrate to the United States, is that such a policy would diminish America’s national sovereignty. By not exercising “control” over borders through actively blocking immigrants, as the argument goes, the United States government would surrender a supposedly vital component of its national sovereignty. But that argument is mistaken as there is no inherent conflict between free immigration and national sovereignty.
The standard Weberian definition of a government is an institution that has a monopoly (or near monopoly) on the legitimate use of violence within a certain geographical area. The way it achieves this monopoly is by keeping out other competing sovereigns (aka nations) that would be that monopoly of legitimate coercion. The two main ways our government does that is by keeping the militaries of other nations out of the United States and by stopping insurgents or potential insurgents from seizing power through violence and supplanting the U.S. government.
U.S. immigration laws are not primarily designed or intended to keep out foreign armies, spies, or insurgents. The main effect of our immigration laws is to keep out willing foreign workers from selling their labor to willing American purchasers. Such economic controls do not aid in the maintenance of national sovereignty and relaxing or removing them would not infringe upon the government’s national sovereignty any more than a policy of unilateral free trade would. If the United States would return to its 1790-1875 immigration policy, foreign militaries crossing U.S. borders would be countered by the U.S. military. Allowing the free flow of non-violent and healthy foreign nationals does nothing to diminish the U.S. government’s legitimate monopoly of force.