A sanctuary city is a city with policies designed to shelter illegal immigrants.
According to Wikipedia, the practices can be by law (de jure) or they can be by habit (de facto). The term generally applies to cities that do not allow city government money to be used to enforce federal immigration laws. They usually do not allow police or municipal employees to inquire about a person’s immigration status. The designation has no legal meaning or definition.
The policy was first initiated in 1979 in Los Angeles, to prevent police from inquiring about the immigration status of arrestees. The internal policy, Special Order 40, states: ‘Officers shall not initiate police action with the objective of discovering the alien status of a person. Officers shall not arrest nor book persons for violation of title 8, section 1325 of the United States Immigration code (Illegal Entry).’
Some of the 31 American cities are Washington, D.C., New York City, Jersey City, Los Angeles, Philadelphia, San Francisco, Santa Ana, San Diego, San Jose, Oakland, Houston, Salt Lake City, Houston, Detroit, Chicago, Salinas, Minneapolis, Miami, Denver, Baltimore, Seattle, Portland (Oregon, New Haven, Somerville, Cambridge, and Portland (Maine). These cities have adopted “sanctuary” ordinances banning city employees and police officers from asking people about their immigration status.