Donald Trump’s election as president of the United States has led to a rise in uncertainty over the future of undocumented immigrants across the country because of the president-elect’s hardline views on the issue during his campaign. A number of U.S. cities, however, have reiterated that despite Trump’s election, they will remain “sanctuary cities.”

A sanctuary city is one where the local law enforcement bodies will not be coordinating with federal authorities to deport illegal immigrants, providing safe havens in the face of Trump’s stand on deportation of these settlers.

“Since the presidential election, there has been a sense of uncertainty among many immigrant communities in Chicago and across the nation,” Chicago Mayor Rahm Emanuel told a news conference Monday. “I want to assure all of our families that Chicago is and will remain a sanctuary city.”

In May this year, San Francisco reaffirmed its stand as a sanctuary city with the San Francisco Board of Supervisors voting to restrict local law enforcement from cooperating with federal officials. Supervisor John Avalos, an advocate for immigrants’ rights who led the negotiations, said: “Last year was a really challenging moment for our sanctuary city policy. But here, today, we have an update to our policy that we get to vote on to ensure that as a city we can unite all together on what the standard is going to be.”

The country also boasts of other so-called sanctuary cities, ranging from Tuscon, Arizona and Denver, Colorado, to Miami, Florida and Trump’s home city — New York City.

The president-elect, during a campaign rally in August, took a strong stand against cities that take this stand. In a speech on immigration, he said: “Block funding for sanctuary cities. We block the funding. No more funds.”

“We will end the sanctuary cities that have resulted in so many needless deaths. Cities that refuse to cooperate with federal authorities will not receive taxpayer dollars, and we will work with Congress to pass legislation to protect those jurisdictions that do assist federal authorities.”

Officials in most sanctuary cities have remained determined to continue with their immigration policies despite such a threat.

“It’s certainly something the mayor's office, the city's lobbyist and our office has started looking at,” San Francisco’s City Controller Ben Rosenfield,  told The San Francisco Chronicle last week. The city reportedly receives up to $1 billion in federal aid, which will be pulled away if Trump’s policy goes into action.

“These are our fellow New Yorkers, we're going to respect them, protect them, they're part of our communities,” New York Mayor Bill de Blasio told Crain's New York Business, even though the city could lose $6 billion if Trump goes through with his plan, the paper reported.