Chicago's Mayor has declared the city a "Trump-free zone", after the US president ended protection for the children of undocumented immigrants known as "dreamers".
Introduced by former president Barack Obama, the Deferred Action for Childhood Arrivals (DACA) immigration policy prevented nearly 800,000 people who came to the US as children from being deported.
Earlier this week Donald Trump rescinded the programme. While existing recipients will see no impact for at least six months, no new applications can now be made.
But in a speech to young DACA recipients at Chicago's Solorio Academy High School, mayor Rahm Emmanuel said: "To all the Dreamers that are here in this room and the city of Chicago: you are welcome in the city of Chicago. This is your home and you have nothing to worry about."
He added: “Chicago, our schools, our neighborhoods, our city, as it relates to what President Trump said, will be a Trump-free zone. You have nothing to worry about. And I want you to know this, and I want your families to know this. And rest assured, I want you to come to school … and pursue your dreams.”
The DACA programme, announced by Mr Obama in 2012, offers renewable protection from deportation for two years to people who entered the United States before the age of 16.
Recipients must have lived in America continuously since 2007 and must not have a criminal record.
Mr Trump's Attorney General Jeff Sessions announced the decision to scrap the DACA programme, calling it an “open-ended circumvention of immigration laws” and an unconstitutional use of executive authority.
“The programme known as DACA that was effectuated under the Obama administration is being rescinded,” said Mr Sessions, who has long opposed the programme.
He added that “the policy was implemented unilaterally, to great controversy and legal concern.”
The announcement prompted hundreds to protest in New York and Washington.
Chicago's Democratic mayor, Mr Emmanuel, served as White House chief of staff under Barack Obama after the 2008 presidential election.
Mr Obama had personally appealed to Mr Trump to keep the programme. He called the termination of DACA a “political decision”, adding that the targeting of Dreamers was “wrong”.
“Whatever concerns or complaints Americans may have about immigration in general, we shouldn’t threaten the future of this group of young people who are here through no fault of their own, who pose no threat, who are not taking away anything from the rest of us,” Mr Obama said.
“These Dreamers are Americans in their hearts, in their minds, in every single way but one: on paper.”
The term Dreamers comes from the proposed DREAM Act, which planned giving unauthorised immigrants legal status in exchange for attending college or joining the military.
The bill was first introduced in 2001, but the latest version was voted down in the Senate in December 2010.
The majority of the 800,000 Dreamers came to the US from Latin America.
Mexico's Deputy Foreign Minister has subsequently accused Mr Trump of creating “anxiety, anguish and fear”.