According to many accounts, the Sanctuary Movement first arose in the United States-Mexico border region in response to a dramatic increase in the flow of Salvadoran refugees to the United States in 1980. Churches responded by providing food, shelter and solace. At the time, all that most people knew about El Salvador was that its archbishop, Oscar Romero, had recently been assassinated after appealing to President Carter to stop sending arms to his country. The refugees, however, brought eyewitness and personal accounts of death squads roaming their country and of church and other humanitarian aid workers being tortured. These accounts provided a "traumatic awakening" for many people, a trauma then intensified by the bureaucratic response of the Immigration and Naturalization Service (INS). Rather than recommending that refugees receive a temporary haven in the United States until hostilities in El Salvador abated and political conditions stabilized, the INS detained - essentially imprisoned - as many of the new refugees as it could arrest and then set about deporting them as fast it could arrange, only minimally observing their rights to legal counsel and an opportunity to petition for asylum in the United States.
In contrast to the relief efforts that followed such dramatic events as the Mexico earthquake and Cuba's 1980 expulsion of political prisoners and handicapped persons, local involvement did not wither this time. Rather, a church community had been awakened to two realities: The existence of widespread human rights abuses in Central America and the U.S. government's refusal to harbor people fleeing those atrocities - an interlocking and "institutionalized process of injustice obviously call[ing] for organized counter measures."
Sophie H. Pirie,
The Origins of a Political Trial: The Sanctuary Movement and Political Justice,
Yale J.L. & Human.
Available at: https://digitalcommons.law.yale.edu/yjlh/vol2/iss2/7