On Monday, Mayor Rahm Emanuel went on record to reassure immigrants that Chicago would “always will be a sanctuary city.”

The statement follows the election of Donald Trump who has threatened to block federal funding for cities that refuse to cooperate with deportation forces under his administration. 

We take a step back to explain what a sanctuary city is, what Chicago’s policies currently are, and how plausible the President-elect’s threats are with Angela Garcia, a professor of Social Service Administration at the University of Chicago.