His dad's stance emphasized the effect of welfare, free school, etc on attracting illegal or ill-veted immigrants, but that's not enough. The real libertarian stance (which is only decentralized governance and individual freedom/responsibility) is in addition to the national border are borders at the state and county levels. If south Americans wanted to immigrate after 1900, they should have been vetted, permitted to lease a small territory, and either be admitted or ejected based on lawfulness.