The idea of the ‘Sanctuary City’ dates back to the 1980s.
Los Angeles was the first one to adopt such a policy, when a 1979 internal policy instructed officers to avoid asking arrestees about their immigration status. The order says "undocumented alien status itself is not a matter for police action."
The movement picked up in through the 1980s when strife in Central America prompted a religious and political campaign to shelter refugees fleeing the region.
By 1989, San Francisco became a ‘Sanctuary City.’
Today, it remains an issue of who is responsible in enforcing immigration. Advocates for ‘Sanctuary Cities’ argue that it not only stretches the budgets even thinner, but it can undermine community relations.
California currently has some 28 ‘sanctuary cities.’ Across the country, there are a total of 123 in 27 states.
For further reading on the background of Sanctuary Cities, see here.