He served as a local deputy in the Congress of Chiapas before moving to the northern city of Mexicali, Baja California, during the 1950s, where he worked as a lawyer.
[1] A member of the Institutional Revolutionary Party (PRI), Castellanos held office as Baja California's 6th Governor from 1971 to 1977.
[1] Castellanos also cleared the Cartolandias, which were communities of cardboard shacks which lined the Tijuana River at the time, which had hindered development in the area.
[1] Former Tijuana Mayor Fernando Márquez Arce credited Castellanos with bringing impartiality to Baja California's political and legal systems.
Milton Castellanos Everardo died of natural causes at his home in the Jardines del Valle housing development in Mexicali on October 10, 2011, at the age of 91.