Philadelphia is home to about 50,000 undocumented immigrants — roughly one of every four foreign-born people who live here, according to a new analysis by the Pew Research Center.
The city's total foreign-born population increased during the last decade, reaching about 200,000, or 13 percent of the overall population.
The analysis comes as the topic of immigration to the United States has become deeply divisive.
Last week, federal courts blocked President Trump's attempt to ban people from seven Muslim-majority countries, while the administration insists it will go ahead with plans to build a wall on the Mexican border.
On Thursday, some restaurants, stores, and other businesses in Philadelphia and other cities around the nation closed as part of a "Day Without Immigrants" protest.
Earlier this week, after a week of immigration raids across the country, Mayor Kenney spoke directly to Philadelphia's anxious undocumented community, saying, "God is on your side."
"Continue to pray," Kenney said in an interview on WHYY's Radio Times. "And work with us to try to figure out ways in which we can legally protect you."
Trump intends to strip federal funds from 'sanctuary cities' like Philadelphia, and Kenney has pushed back, saying that he has no plans to change the immigration policy and that the administration would take "every opportunity we have to protect our citizens and protect our people who are living in our city."
The Pew analysis relied on data from 2014, the last year for which figures were available. In 2005, roughly a decade earlier, undocumented immigrants accounted for a slightly higher percentage, about 27 percent of Philadelphia's 170,000 foreign-born residents.
The research showed that compared with four large Northeast cities — Boston, New York, Baltimore, and Washington — Philadelphia's undocumented immigrant population was the second-largest, fewer than the 525,000 of New York and more than the 35,000 of Boston.
"The unauthorized immigrants tend to go where they can find jobs," said Jeff Passel, senior demographer with the Pew center, "and where there are other immigrants, where they have friends and families and communities."
The 25 percent of Philadelphia's undocumented foreign-born resident population was greater than New York (16 percent) and Boston (20 percent), and about the same as in Washington (26 percent) and Baltimore (29 percent).
Philadelphia was equal to the country as a whole, for which the undocumented share of foreign-born residents was about 26 percent, or 11.1 million people.
The numbers shifted when converted to a percentage of a city's total population.
In that figuring, Philadelphia's undocumented immigrant population stood at 3.2 percent, lower than New York, Boston, and Washington, and ahead of Baltimore.
Philadelphia was slightly lower than the overall national figure of 3.5 percent.
In Pennsylvania, undocumented immigrants were concentrated in Philadelphia, the analysis showed. The city had about 28 percent of the state's 180,000 undocumented, 12 percent of its total population.