A sanctuary city is a city that has adopted a policy of protecting undocumented immigrants by not prosecuting them solely for violating federal immigration laws.
According to the Center for Immigration Studies, Baltimore, Prince George's County and Montgomery County are all considered to be sanctuary cities.
In November, former Baltimore Mayor Stephanie Rawlings-Blake declared that the city is welcoming to immigrants, though she stopped short of calling it a sanctuary city.
Rawlings-Blake's declaration was a response to President-elect Donald Trump's immigration proposals to create a Muslim registry and deport up to 3 million illegal immigrants. Trump has vowed to hold millions of tax dollars if city officials do not cooperate.