Another freedom described briefly, with support form Pope Pius XII:
25. Again, every human being has the right to freedom of movement and of residence within the confines of (their) own State. When there are just reasons in favor of it, (they) must be permitted to emigrate to other countries and take up residence there.( Cf. Pius XII’s broadcast message, Christmas 1952, AAS 45 (1953) 36-46) The fact that (an individual) is a citizen of a particular State does not deprive (the person) of membership in the human family, nor of citizenship in that universal society, the common, world-wide fellowship of (women and) men.
How often have our current bishops cited Pacem in Terris in their argument for immigration reform in the US?
Catholic Sensibility 
This passage has often been cited in documents from the US bishops, including their 2003 joint pastoral letter with the Mexican bishops. The Pontifical Council for the Pastoral Care of Migrants and Itinerant People cited Pacem in Terris several times in a 2003 statement.